I was wondering if anyone has a camper they are pulling with there V6 T4R. I have a 06 sport V6 4wd and im not sure how big of a camper we can pull with it only being 5000lb capacity. Im not really wanting a pop up camper but im wondering what we can actually pull with it.

Well, I haven't pulled a camper with my '08 V6 4x4, but I do pull a fishing boat.
This boat tow can be quite a tow, over 11000 ft passes are common for me here in Colorado. The boat is approx. 1500 lbs, but loaded with camp gear and firewood, rear cargo loaded to the window level, make that 2500 lbs. No problems at all, more responsive that my previous Expedition. This T4r is quite a little workhorse.

I tow a 3000 lb pop up camper. Add bikes on the rack, loaded camper, and loaded truck, maybe 3500 lbs total. Don't even know its back there and get around 14 mpg average measured. I'm looking at buying an 18 to 20ft runabout and am not concerned about pulling or launching it as I also have 4WD for the ramps.

If you get a hard side, keep in mind the wind resistance will be more noticeable than the weight, especially if you are going 70 and or there is a lot of wind.

I think I can add a little here since I was in the same boat last year.
Towed a pop-up (2200lbs) with my '03 V6 Limited and didn't even know it was there. Bought a 20' hybrid last fall and was shocked at the difference.
I had it weighed and was about 3800lbs loaded to camp. Had myself, the wife and 2 small kids in the vehicle. Well under the towing capacity and used a weight distributing hitch for safety and comfort.
By the 3rd trip it was time to upgrade the tow vehicle. The wind resistance was the killer (even though our trailer is only 7.5' wide as opposed to the standard 8') as well as the gearing of the transmission. To tow that weight you need to keep it in 3rd gear at all times. It struggled to hold 60mph on the flats and bogged down on the hills. Being a Toyota it would probably handle it all day but its not comfortable at 3000+rpm.
This spring I traded in for an '04 V8 and couldn't be happier. The extra torque and 5 speed tranny made all the difference in the world. 4th gear on the highways and even 5th on the flats sometimes, easily held 65mph and it would accelerate on hills without downshifting. Better fuel mileage too.
The V6 will do it (I see minivans with less power pull similar all the time, I just can't see it being comfortable or good for the vehicle on long trips)
If you do it, make sure you have a tranny cooler and use a sway bar (The T4Rs short wheelbase makes it prone to sway). Better yet use a Weight distributing hitch if you're over 3000lbs. Just make sure you have the upgraded hitch which is approved for it, the base one isn't.