Antenna removal

What you could do is what I did when mine broke as a temporary fix. Remove the head with the wings and leave the mast. Get a PVC pipe cap that will fit over the opening in the post. Put sealant around the top of the mast and put the cap on. If you think it is needed, take some Gorilla tape and tape around the cap. Then you will have a leak-proof setup without the antenna. You will still need to watch out for your cover. However, if you were to remove the mast, you would need to figure out how to seal not only the screw holes, but also the larger center hole through which the wires pass. You could remove the mast and use a plate larger than the mast base and seal around it with lap sealant also, but the first method is faster and will work. Plus, the mast is still there if you want to put an antenna back up there.

Or, possibly you could use the hole where the  antenna wires came through as a chase to run wires to a roof mounted solar module. That might be far more useful to you than the antenna is depending on where you camp.