Well depending on who made you boat you may be able to call the manufactor and see what they do to mount a pd/terrova on your boat, I had the problem that changing my tm to a terrova I didn’t really have a way to mount the motor close enough to the edge to work, thus I had to drill tap and install a http://www.boatersworld.com/product/MP63514494.htm on top of my exsisting tm mount, at the time the time I did it Ranger hadn’t even attempted to put a terrova on my boat, so they were no help, I have no idea who makes the mount that came on my boat orginally never seen another for sale. My boat is fiberglass too, which is part of why this is so hard to change up.
Otherwise I think a quick call to Minn Kota (800-227-6433. Monday-Friday between 7:00am and 4:30pm)
Boat cover is an issue, my TM had to come off now if I want the cover on, I could probably have it modified, but it’s not a big enough issue to me since I rarely cover my boat and trailer it. Overall the difference in the TM between the two styles I believe it going to mess with most custom covers, going from a cable drive to a PD.