We have the Crusader 320 RLT. Overal length from pin to bumber is 36.5'
The dry weight is 10245 lbs, 1753 pin weight.
Remember, compared to a pull trailer of same length you will be approx. 4' shorter overall due to the overhang over the box.
With a 36-37' 5th wheel your over length will be fairly close to what u are pulling now.
Weight will not be a problem for your 350.
Final thought, my Chevy 2500 pulls the trailer no problem and these trailers are balanced very well, I don't get any sloppy truck bouncing when going over bumps, rail tracks.
07- Classic 2500 LT CC 4x4 SB Duramax/Ally
13-320RLT Crusader TE
Reese 16K Kwik Slide/Prodigy brake contoller