I've changed my door back to what the pre-2020 models had. It will now take one of the keypad locks, but it's not a project for someone unless you're retired with lots of time for trial and error engineering.
Just a reminder that firmness and density are not the same thing and they are both critical. Firmness is how firm the cushion will feel on Day 1. Density is how long it will stay that way. The problem with Tab cushions most of us have had is that they start nice but very quickly sag/soften. That's because they're extremely low density - I did some measurements of this somewhere back in this thread and these are crappier/lower density than even the worst Chinese import sofas - no wonder they sag! So if you're replacing, don't just choose your desired firmness, but for the love of all things holy, make sure they're also high density - aim for 2 pounds per cubic foot MINIMUM if you want them to last.
Have you considered a truck box? This one came from Tractor Supply, but a search should find a lot of other options from forum members. It was more work than a "simple bolt on", but not too bad and well worth it.
Before you spend money at the RV dealer, check to see if your F150 already has a brake controller factory installed. If you have a 7-pin connector somewhere near the hitch you probably do. The display on the dash also has some info about towing and a way to set the brake sensitivity.
After reading through this thread. It appears to me you had issue with corrosion no matter which transfer fluid you had in the system. Correct me if I'm wrong. My Tab320 was built in june of 2020 & has the Century fluid. I have replaced the fluid once & I am planning to do it again this spring. I am not convinced the Rhomar fluid is worth the cost. This thread is just one of several that supports my conclusions. Century fluid has & still is used in many hydronic heatring systems with no corrosion issues. I believe the issue is with Truama's manufacturing and type of alluminum tubing they use. I am retired , but when I was working I was a aircraft structures technician. I worked with several different grades of alluminum. Truama has a chioce & I believe they went with the less expensive grades.
@DanSees yes, you have blown my cover! The only reason I have any information at all is from the phenomenal user group here at the Forum. This group, and other FB commenters, deserve every bit of the credit. Like your aircraft mechanic skills, there is a massive amount of talented people here. Me? I learned how to use a hose clamp tool recently! My only real skill is Google search.