At minimum you need a rubber bed mat, turnbuckles and truck tie down points. If you plan to tow behind the camper, you need a receiver strong enough for an extension, a proper length extension and trailer wiring extended to your ball. There are many ways to tie down the camper to the truck and how to tow, so I will let others argue which is better - My preference is Torklift products for both.
Whether you need suspension help will depend on the camper you choose. Additional OEM spring preload and heavier stabilizer bar is typical but not always needed.
