By big truck... you mean...
This?
I have not had any problems parking a full size anywhere, except perhaps a 2004 Ford F450 long box, dual wheel, crew cab.
Turning Radius sucked.
But, Then again I take the tractor in the above photo and park it in regular vehicle spots at the local resturants.
Anyways, Depending on your use, and assuming fairly light duty, a 5.4L should do you okay. But If your going to have a camper in the box on a regular basis I would go Diesel, just wait for someone to make an aftermarket rad that doesnt self destruct.