Here is my bros pickup. weve both logged thousands of miles with a sled deck in a short box. Just make sure the deck is securely fastened to your pickup and you shouldnt have any issues.
Chevy 1500 with airbags....Silverlake Deck w/ beavertail
My sled is a 159, my partners is a 151.........No issues around town, on the freeway or the switchback turnarounds on the mountain.
The picture is a bit deceiving, the end of the track hangs out beyond the end of the beavertail.
2 sleds on a 1/2 ton squats it down a bit but not enough to be a problem, I have the airbags for heavier loads and it works great for the deck too. 2 sleds on the deck and 30 lbs psi in the bags is perfect.
Here are two sleds on my truck. One is an XP w/ 154" and the other is a D8 with 155". All the weight is forward of the seat so it's not a big deal to have a little hanging off. I went with this style deck because I could collapse and expand the sides.