Hate to say it but could you return the camper? Its probably far too much for a half ton truck and it sounds like its too long. Others may know more about the length issue and the tie downs. Most truck campers belong on 3/4 ton trucks. You are probably looking for a 1200 lb camper or less and then the next problem is that you cant carry much because you go over the limit which is around 1600. You should probably be looking for a short soft side camper or go with a travel trailer and get three times the living space yet be within the towing capacity of your truck. A 1/2 ton will be better able to tow what you need than carry what you need. It would be safer to put the camper on a trailer so its properly secured.
