You should be able to order the F-550 with or without a CHMSL (Center High-Mounted Stop Lamp), but, remember that it is an incomplete vehicle, and many are ordered to be used with a big body which will have the needed lights.
I suggest you order your truck with the CHMSL to use with your flatbed when the camper is dismounted from (off) your truck.
Depending on Federal and Sate laws, you may, or may not, need to have lights on your camper body as it will be cargo on your flatbed,
Even if you don't legally need to have lights on the camper body, I suggest lights for safety reasons.
Check out the following regarding CHMSL on truck caps in Maine:
" The letter from Lt. Dow of the Maine State Police agrees that "you are correct in determining that a dealer must include a third brake light when a cap is installed on a truck required to have a high mounted brake light. However, it is also correct that the owner of a truck equipped with a cap is not required to have a third brake light on the cap." Maine has concluded that it "will tell the owners of pick-up trucks that the law does not require them to have a third brake light on a cap, but that dealers are required to include them." "
Mr. Ron Stoddard J & M Camper Sales RR6 Box 526 Augusta, Maine 04330 Dear Mr. Stoddard: This is in reply to your letter of August 7, 1997, requesting a clarification of laws pertaining to center stop lamps on truck camper caps.www.nhtsa.gov
agreed. I’ll be doing it for safety reasons. Looking at what’s on my travel trailer now and matching it to the NHSTA guidelines.