Someone more knowledgeable than I needs to address the amperage draw, but it does sound too high simply because when you're out of the water you are at the "zero load" state. But in this state you have 4.5 amps of pure drag, which sounds excessive. The heavy grease is undoubtedly your culprit, as you suspected.
I believe you can install your shaft seals without removing the aft hull from your WTC cap. You can get a little abusive when removing the the old hardware, as long as you leave a little shoulder on the cap to which you will epoxy your brass tubes. Did you check out that page I linked on my earlier post?
Maybe you could cut the tips off with a hot knife. Or I have a cheap hack saw frame that holds the blade at one end, so the other is unsupported and can be used for something like that. That or if you don't have a dremel, you could get one now. Some of the best money you'd ever spend.