Use Tefgel or similar if tapping the embedded plate. Otherwise dissimilar metals will corrode and it'll be near impossible to remove the fastener
I’d like to help a bit here. I installed tracks for my Genoa on the 49, and there were aluminum plates in the deck.
Here are some very important ruies
If you are not totally proficient with drilling and tapping holes into aluminum, hire someone who has done this professionally. It’s easy to break a tap in aluminum, and a broken tap in your deck is a nightmare problem
So, assuming you are up to this…
Purchase excellent quality taps and tapping fluid. You are going to be tapping (most likely) 1/4-20
Get a drill guide, which ensures you are drilling dead square to the deck
Make sure that the aluminum plate is indeed bonded into the Fiberglas.
Look up the tapping drill size.
Using the guide, drill a hole one size smaller than the tap size
When you are drilling, ensure that there is proper lube oil on the drill. WD 40 is no appropriate.
Have a shop vac on deck.
Once you drill the pilot, vacuum out the hole.
Now, carefully, (with lube on the bit), drill the tap size. Then vacuum out the hole agsin
Take a counter sink, and slightly counter sink the Fiberglas, This will give the 4200 sealant a good place to start sealing the hole.
Now, get a drill bit which is clearance size for the bolt you will be using. You want to drill just deep enough to remove the Fiberglas. You want a clearance hole in the glass, and tapping only the aluminum
Now, using a good quality T tap handle, load up the tap with tapping grease.
Very slowly, start to tap, and keep backing the tap out, and vacuum the hole every time you extract the tap.
Take your time, and ensure you are tapping dead square to the deck. The aluminum is likely 6061-T6, which can get “sticky” when hand tapping. Just take your time, and be very careful not to break the tap.
Once you’re totally through, vacuum well again.
When you install the hardware, wipe the whole surface with acetone first. Use 4200 to seal everything .
hope this helps