Yes, if your vehicle (Jeep) has removable doors, it is legal to drive without them. Hoever, you must have sideview mirrors to be legal. I believe the enforcement of that is very discretionary, because some old cars did not even have both side mirrors, only a center rear view. I guess, Jeeps come with mirrors when doors are on, so mirrors have to be there in some way when doors are off also.
Its best to avoid any problems to get the add-on mirrors for when your doors are off.
I drove everywhere with no mirrors on my old TJ, and never had any problems, but its not very safe and I could have got busted many times for it.
Darren