So in case anybody was wondering...
As I said, I'd been able to drill with a pin vise in resin up to 1/8 easily. Precision pin vises are truely a marvel. Went up to 5/32, chipped too much, asked around and there we were.
Brought my caliper home for the weeked along with a complement on drill bits in increments of 1/64 so as to go from 9/64 to hopefully 1/4.
Problem: the HS-129's fuselage made 0.248" at its widest. Same size as the head of the flightstand. Thought about it, opted to house the 3/16 magnet in and leave it at that. Might as well have simply glued it under the fuselage but I was not very excited at that prospect, using worktroll's advice of putty/blue-tak or similar stuff was kind of more appealing, would've probably glued the head of the flight stand on the fuselage then worked the flight stand to allow the head to be removable...but I really wanted to use my new hand drill (bigger then pin vise, up to 3/8 drill bits, not as good a product as pin vise but still good) and magnetize the whole thing.
So I went along and drilled into the resin in 1/64 increments.
While the resin chipped a bit, I was able to successfully and with minimal chipping to bore the hole up to 3/16 size so as to be able to house the magnet in the fuselage and glue it there. Tried to go to 13/64, resistance was too great. Lost one of the magnets though, don't understand how. Eyes got too foggy due to fatigue, will try to find it again tomorrow but more likely I'll have to buy some.
So yeah, you can successfully drill into brittle resin up to 3/16 inches with little damage to the mini.