MIke,
I'd bet you could sell 20 of them to people on this site pretty quickly. Maybe a lot more. Looks like 4 are already spoken for. A much bigger market if you tie into the Trailblazer group as well. Make up a few for "beta test" models and sell them for whatever they cost plus some profit so it feels more like business than charity. Get user feedback and comments, then decide if you think it is a viable idea. I don't know how non-commercial aspects of this site jives with accessory marketing, but since it is a product specifically for owners, there is probably a way to make it feasible but that decision is above my pay grade.
Figure out what the material, supplies (paint, etc.) and shop costs (welding rods, electricity, etc.) would be for 20, then for 100 (probably much cheaper on a per-unit basis than for 1 or 2) then add 20% for scrap and screwups. Then figure out what your time is worth and add a factor for admin and other inefficiencies.
If it appears to be a financial opportunity that could be worthwhile, decide if you really want to do it, and are willing to make the time commitment necessary to see it through. Or see if you can subcontract the work and just sell them without having to make each one. Might be a better way to make a buck than welding them up yourself. Once that is done, test the market for interest.
Then plan to attend one of the rallies with some merchandise ready to sell. I think you could sell all you could carry. Take a portable welder to install them, or a drill and bolts for those who don't want them permanently mounted. Maybe look into making some other products as well. Sounds like lots of people would like a nice rack/box on the tongue. I would. Different configurations may make this more complicated, but worth exploring. Maybe mud flaps with a metal frame (like the trucks) as well. After seeing that my exterior plumbing system had disappeared after a blowout, I would consider a braced mudflap or guard. Probably other accessories as well.
Two things are apparent regarding accessible storage when the trailer is folded (from a marketing standpoint)
1. Other than the bumper, ain't none you can get to without raising the roof. The need is there.
2. TM owners are differentiators; they paid more for their units than they would have paid for something else, they like their units a lot and many would be more than willing to spend some money to improve usability and convenience.
As Dennis Miller says, "that's just my opinion; I could be wrong."
Wayne