First, if you are in the delightful position to be able to buy a new truck and camper at the same time, more power (and cash) to you! Here's the lowdown, though. It's best to examine your RV needs first, choose the camper, then go about the business of picking out what's the best pickup truck to support your choice of a truck camper.
When truck campers first appeared, there weren't a lot of options available. These days options abound, including slide-outs, extended cabover length, metal siding, fiberglass siding, large bath, small bath, and on and on it goes. Really, much of it boils down to weight. The more options, the more the weight, the bigger the pickup to support the whole endeavor.
Sit down, decide what you really have to have in your camper, then shop the market. For those looking for a new model, fresh off the dealer lot (or ordered from the factory), you'll have a much easier time determining how much the new camper will weigh. When buying a used rig, your choices are obviously fewer--it's what's available on the market now, or wait and see. Hopefully the camper you settle on will have a legible manufacturer's certification tag that shows the weight of the rig. But beware, dealer (or owner) added options won't likely be included in the weight listed on the tag. If possible, have the camper weighed so you know what you're getting into.
Once you know the weight of the camper (and don't forget to add the weight of water, propane, gear, groceries, and passengers) then it's time to evaluate what truck will effectively (and safely) carry the weight. Unless you're willing to go to a "pop up" style truck camper, which may be great in warm weather, you'll find a half-ton pickup probably won't support most TCs. Even the common 3/4 tonners will not meet the need of larger and heavily optioned campers. But don't cave in and try and make a too-small-truck fit the bill--you'll regret it and maybe pay for it in a dramatic way.Chicken or egg? Camper or truck? Pick the camper first, then the truck, and you won't have a 'Humpty-Dumpty' situation on your hands--leaving you to pick up the pieces.
