The biggest pitfall is buying the truck before buying the truck camper. You've already done that. It's ok though ... most people do.
Go as light as you can on the truck camper. It will be easier to tow if you also go as short as you can and doesn't require a hitch extension. Tires are the biggest limitation. You could go 19.5s, but you can't air them down for the beach. Better shocks and adding good sway bars will help. To level, you can use air bags with extended bump stops or stableloads, timbrens, supersprings, or stableloads by themselves.