A/C swap? On 320 S Dimensions of inside box?

No where near 4” of space.  More like 1/2” or so.  You should be able to see it by looking from the outside thru the vent.  

2½" wider! Sounds like a major change! The electric box uses that 'extra' space on the left, but also note the aluminum framing in the photos... 'moving' that framing over will be a trick, esp with the slope of the ceiling coming down...

Is the Midea shorter vertically?

Keep us updated!

That's an interesting bit of info. Bigger isn't necessarily better....

Sharon_is_SAM said:

Not sure a bigger A/C is the answer.  Already the 5,000 btu unit is oversized for the TaB interior.  If the interior cools quickly, and the compressor turns off too soon, it will not provide for adequate dehumidification.  This has been a problem with the TaGs.

I went up to a 6000 BTU LG very inexpensive Danby replacement last year, and it was wider so I had to do surgery on the frame in the A/C box, but higher rating did definitely help with cooling.  In the lower altitude southwest our problem wasn't the compressor cooling the unit too quickly when 90-105F outside...  our problem with the Danby was getting more than ten degrees below the ambient outdoor temperature.

@51chevy ; @ChanW ; @Bayliss ; You can widen it a bit more.  In the pics below, I took out an aluminum vertical support on the right side, since there was another one a few inches away.  That's not just surgery to the front wood trim, but surgery to the internal cage. Looking at Bayliss's images above, I then flipped the angle bracket over, and used screws and strong adhesive to put it in place to accommodate a 17.5" wide air conditioner. I think the original Danby was only 16" wide. The height of the box is up to 12.3" high unit.

The Midea Easy Cool 6000 is 13.4" high (1.4" too tall) and 18" wide.  That's another half inch wider than I widened my box...  but as you can see in the pics, it will accommodate that width if you just place the front to back angle iron (well angle aluminum) a half inch to the right. Just barely.

The problem is, if the 8000BTU Midea you were looking at is also 13.4", it won't fit without hitting the aux fan at the top of the box and interfering on the top left side. You really need 12" or less on the height with the existing box. And even with the modifications shown below, I'd keep the weight of the replacement air conditioner under 45lbs.

You can replace the whole box, and weld a new frame into the existing side and roof supports, then create an ash veneer plywood enclosure for it, but that's a considerably larger effort.  You can look for a 6000 or 8000BTU unit that's 12" or less tall, but they're rare.  I put in an LG 6000BTU+ air conditioner last summer (LW6017R) that was 17.3" wide and only 11.125" high for $150 on sale, but it is more sensitive to having plenty of fresh air coming into the A/C box... you cannot seal the back of the A/C to the camper side and feed fresh air only with the roof vent fan like you can with the 5000 BTU A/C units.  Too warm of intake air and the LG will just turn off the compressor for 15 minutes before trying to cool again.  But comparing a Frigidaire 5000 vs an LG 6000+ BTU unit, I get 40-70% cooler temperature differentials in half hour and one hour testing compared to outside conditions when it's in the mid-90s, even though the LG is only 11.5 EER.

Good luck, and let us know if you find any nice 5000-8000BTU units that will fit within the 12H by 18W limits of a modified cage box. Besides adding a dehumidifier, switching to a better set of electronic controls than the stock Danby, or switching to a higher 170-250CFM flow rate even at 5000BTU would both help.

@DougH, I've yanked my seized up a/c and I'm looking at ways to improve air flow around and through the unit to help pull heat off the a/c itself.  My 2015 has the roof vent but did not have a fan in the ceiling as shown in one of your pics above. I would assume the idea is to allow a bit more air to be pulled into the a/c cabinet to help cool it off, and the fan would improve the volume of air somewhat.  Adding the fan would be no problem for me but I have a couple of questions.
Has wind blown rain ever presented a problem for the fan, either electrically or mechanically on the bearings?   And, has anyone had better ideas for increasing the air volume such as using a larger vent or baffles to try to limit the hot air exiting the cabinet from mixing with the cool air it's trying to pull into the sides of the unit to keep it from overheating?
Thanks for any info you might have!

@DougH, how do you like the GeoPro, and is there anything you miss (or don't) about the T@B?  Did you buy new or used?

I just bought a 5K BtU Frigidaire A/C unit to replace my old Danby.  For anyone who has done this swap, can you give me any tips on installation.  The old Danby had slanted aluminum plates taped to the exhaust outlet on the back.  I  am presuming that this was to separate the air intakes on the sides from the exhaust out the back of the unit.  The Frigidaire seems to be exactlythe same dimensions as the Danby, although it might be about 1/" shallower front to back.  I suspect you really want to get those diverters smack up against the output louvers so the side intakes don't suck the hot air back in.  I guess I could extend the diverters by a 1/2" if necessary.  Also, the Frigidaire instructions specifically say not to drill a hole in the bottom plate so the unit can drain into the drip pan.  So I can't figure out whether I should or not.  How else is it going to drain?  Lot's of thanks for whatever you can tell me!