One of those quads is riding in the truck.
Figure 8.5' for the SxS, then one quad loaded sideways in front or behind (4'), and you've taken up the 13'.
If your trailer doesn't have a division wall (which I suspect) you may be able to run one quad up by the entry door, then the SxS, then the second sideways in the rear. But the 21-26 layouts I've seen wouldn't have enough room for that quad in the front.
2005 2500 Cummins/48RE/3.73, QCLB, 4wd, BigHorn, Edge Juice w/ CTS + Turbo Timer,Transgo Shift Kit ISSPro Oil and LP pressure gauges, GDP 20/2 filters, Custom Diesel Steering Box Brace
'10 Forest River Shockwave Toy Hauler 21'
Honda EU3000I Genny