When I installed my Winegard, I had to install it so that it folded down to the side instead of to the rear.
It should be fairly easy to rotate the base. Raise the antenna and remove the knob assembly on the inside being careful not to lose the spring and washers. On the roof, clean off the sealant and remove the screws. You will probably have to use something like a putty knife and work under the base and pry it loose. Rotate the base to the desired position. If the coax goes through the base plate, you probably will have to drill another hole. Apply sealant and screw it in place then apply sealant over the screw heads and any holes.
I would suggest sticking with the Winegard, especially if there are VHF stations in the areas that you will be in. The 'batwing' with the Wingman is the best RV antenna available.