Also have a long trailer.
4 corner jacks and the x-chocks still didn't make it as solid as the Mrs. wanted.
Bought the cheap stabilizer from camping world and first trip, it made a huge difference. Second trip, didn't seem to work as well. When I took it off, I found one of the pins had broke. I'm going to have to do a fix to it to make it work again. I'd take it back for a replacement, but there is no Camping world where I live (bought it while on vacation) and it's easier to fix it for me.
This is the one I bought. I think it will do the trick once I fix it.
http://www.campingworld.com/shopping...abilizer/34337