Best Of

Very smart @sportcoupe. Simple, but functional. I apologize for being one of those OCD folks. As only being a retired machinist with too much time on my hands, my "obsessions"  should not be taken too seriously. The quality of your work is excellent. Thanks for sharing.

First I will say the factory 4 vertical 1/2" bolts are more than adequate alone to tow the Tab. No side fasteners are required.

While bolt shear strength isn't published. It is estimated that shear strength is 60% of tensile strength. A grade 5 1/2" course bolt has a tensile strength of ~17,000 lbs. 60% of that is 10,200 lbs. There are four factory bolts. The Tab is 2,000 lbs dry. 

Now if you are worried about twisting of the frame sections without side support and suspect that is what the side flanges are for, well... read on.
The factory coupler mount side flanges are not fastened to the frame so they provide very little, if any, resistance to frame twisting. Furthermore, there is no structure on the inside of the frame to prevent twisting there either. Nucamp doesn't see a problem and neither do I. 

Twisting frame just isn't an issue. The top and bottom plate with the vertical bolts create a boxed section that is inherently resistant to twisting.

For the OCD folks that don't like looking at empty side couple holes on the Demco coupler upgrade, I have a very simple solution. Get four bolts 1/2"-13 x 1" long and four nuts and four toothed lock washers. They will provide pseudo side frame reinforcement and fill most of those pesky empty holes. There is no frame behind the forward side hole so it must remain empty. The wood pictured has a curve and allowed me to fit the washers and nuts into the skinny gap between coupler and frame to attach the bolts. My fingers were too fat

@sportcoupe thanks for sharing this! I think I see that you reused the lower plate that reinforces the jack tube and has the OEM's chain mounting bolt holes. 

I followed in your footsteps and today I finished installing a Demco coupler with an Ultimate Trailer Jack. I decided to go with this model coupler and bought from the same source you did: https://www.crofttrailer.com/16854-81-demco-a-frame-2-coupler-with-chain-anchors-10-000-lbs-capacity/

I initially thought I'd mount the coupler with the sides closer to the A-frame, but I couldn't do that and reuse the bottom plate that forms a bolted box, so I mounted it forward where the jack hole on the coupler lines up with the one on the bottom plate. The hole on the bottom plate was 1/16" too small to clear the Ultimate Jack, so my first job was to scribe the target size and enlarge the hole with an abrasive grinder.

I used the bottom plate as a template to mark the hole locations for the four mounting bolts on top of the Demco coupler. I managed to drill the holes using a cobalt stepped drill bit, going slowly and using tapping oil. I painted the raw metal edges of the holes to help prevent rust.

NuCamp welded a panel into the front of the A-frame to create a box structure from the C-shaped steel members.



These images show the installed coupler. The Ultimate Jack normally mounts with its pin shaft pointing back at the trailer. The aluminum platform interfered with that, so I rotated the jack 120 degrees. I had to drill and grind out one of the mounting slots in order to center the jack's mounting plate in this orientation. The Master coupler lock fits the Demco much better than the OEM coupler. My latch lock was fortunately long enough to get through the wider Demco coupler.



The sides of the coupler leave about a half-inch gap, but they didn't fit tight to the A-frame on the original coupler. I do think it's wise to use the bottom plate with the original bolt configuration. And this upgrade is reversible should we even need to do that.



I could never find a specification for the offset difference between the OEM coupler and this cast Demco model. @sportcoupe mentioned two inches, but I think it's more like one inch. Here are profile views of the OEM coupler vs. the new Demco coupler.





I'll check, but I don't think I'll need more drop on for my hitch's ball mount. It was too cold and late in the day today for me to test the upgrade, so the easier operation I'm hoping for is still hypothetical. I'll report after I've had some time with it. I think I'll like the Ultimate Trailer Jack, but I don't think I can reuse the 7-way connector holder I had mounted to the BAL jack. I doubt that the convenience of the eZ-latch and Ultimate Jack over the years will add up to the time I spent doing this install, but I'm okay with irony. ;-)

@AnOldUR I'd agree with you except the OEM's BAL coupler did not fit tight to the sides of the A-frame. It also doesn't overlap very far in terms of preventing a shear load on the bottom end of the four mounting bolts. The shear force is borne across the top and bottom of four bolts, not just one end of a single bolt. Given the difficulty of fabricating shims and drilling through the sides of the boxed A-frame, I'm not likely to pursue that belt to go with the suspenders.