Trailer not truck camper but we have made the switch (long story, not sure we would do it again)
Assuming you aren't overloading the truck, I can't buy the effort to open the slide being a serious consideration.
How long does it actually take to look as you are walking from the cab to the back to make sure it isn't going to hit a tree and then 20-30 seconds to push the button.
Can you access the fridge, bathroom and bed with the slide in?
Only real positive side we've found is it takes hardly anything to heat. Down to the low 30's, a 1500w space heater does the trick with the furnace never kicking on.