Member brenndatomu posted and reminded me of this guy below using a treadmill as a conveyor. Got me to wondering if you could sacrifice the middle part of your truckbed to put a treadmill in it, lol. You might be pressed to carry a facecord in a truckbed sacrificing the middle section, though. Wonder if a converter would run a treadmill from your truck motor or would you need a generator? It would certainly be a conversation starter for buyers! You'd have a stack either side of the bed and could just throw it down or kick it onto the treadmill and it would spit it out into a pile at your stack spot. Wonder if it would save time, lol. If it worked, it could be a word-of-mouth marketing advantage, "the guy with the treadmill in his truck that spits our firewood." Oh, wait... they make those bedroller unloader gizmos that empties the entire truckbed! Do those work? Does buZZsaw BRAD have one of those from HF? Put a motor on one and that would be the ticket; now I wonder if there are any motor-driven ones!
I design conveyors for a living. A treadmill would not be what you want to go with, but if you look at farm elevators as an inspiration, you could do more than you think.
Having said all that, you could potentially make a false bottom and just set the treadmill in the center. With a false bottom, you could also angle it in toward the treadmill. The biggest issue is going to be how much weight you want to put in the pickup. You would have to see what the weight limit on the treadmill you have will take. Also, with a false bottom, if you didn't want it you could take it out.
I use it where i have a full load of splits. Ill pull what i can reach if im stacking as im unloading, then ill crank it, repeat etc. If you do it right (which i seldom do) it works .
Ive spread a tarp over the conveyor for dirt, mulch etc and it worked good. Tarp alone works for small amounts but gets tattered up. I have a plastic bed liner and it slides rather well over it.