I sprayed my hull (inside mirage slot) with cooking oil, I then fitted the plug and proceeded to fill the gap with "Selleys All Clear" http://www.selleys.com.au/Selleys-All-Clear/default.aspx
(I think "Goop" is an the equivalent in USA) and then let it set for a week. It worked great for a while but then proceeded to lift when fitting/extracting, repeated the process a couple of time and have since come to the conclusion that it's really not worth the effort or cost. Mind you most of the time my drive is in place as I very rarely sail without now.
If you were to sand and (very carefully) flame treat (burn) the plug it may get a better bond and last longer than what mine did. It also pays to mark one end as the front and one as the back when doing it, well in my case anyway it would not fit as well when turned around. I thought about molding an entirely new plug out of silicone but it would weight a fair whack, not sure if you could make one from styrene or balsa wood first and then use a silicone for a seal and get a better bond.
Good luck be interesting to see if you come up with something.