To update this old post since I forgot (sorry!) I ended up calling supergen products and getting the dual fuel 2800 model since it's the smallest I can run my 15k A/C on. It works great!
I can even use the regulated BBQ grill output on the back bumper to run it off the trailer's supply. However I found out that just using a straight propane hose has it's problems, the Champion regulator that came with it has 2 stages, a low and high. In order to run it off the trailer I have to adjust the gas flow with the valve after starting and loading it down. So I believe the ultimate solution is the take apart the regulator and remove the high-pressure part and just use the low one. There was a YouTube video of someone else doing the exact same thing however he didn't name it very well and now I can't find it! But here's the one I shot with using a straight hose:
https://www.youtube.com/watch?v=Rzx5ITHnDswEDIT: here it is!
http://www.irv2.com/forums/f93/champion-3400-dual-fuel-on-rv-propane-system-344289.html
