Most states require you to have a rear bumber, I know Tennessee does, ask me how I know, also a front bumper, I see customs all the time in Knoxville and Morristown, get pulled over all the time because of no back bumper.
I have a 69 VW with no front and no rear, got me a nice $250.00 ticket and still had to have bumpers put back on it.
When I went back to school a few years ago, we toured the school, and in the auto body shop, one person was cutting the pan off a nice s-10 to put the bumper back on, he said it cost him a ticket of 300.00 and if he drove the truck back on the road again and got caught without a bumper a second time, they was going to impound the truck.
SO best thing to do, is leave your bumpers on, and check with your local law inforcement, so you don't take a chance losing your truck.