I just went through a similar problem on my boat but had to replace entire floor. I used 3/4" plywood candy coated in resin, non osmotic primer, and a coat of Interlux Perfection with the grip material in it. It came out awesome! Why not tape off area you don't want to change, scuff up existing surface you are trying to stick to, get your 3/4" piece of plywood cut to size, candy coat with fiberglass resin, let it cure until it hardens, scuff bottom of plywood again to get a bite, do any drilling of holes and retreat holes with a tiny brush to seal, let cure again, set piece on existing deck to be reinforced, predrill deck with whatever anchoring device you are intending to use, wet both surfaces again with fiberglass resin, let cure in place, paint or whatever you are going to do, bolt down and mount seat. Or you can buy two fiberglass pedestal bases on ebay from a guy named boyd2may. I just got em last week. (It took awhile since he fabricates in his own shop). Anyway, he has two sizes, which by the way has a little storage area with a latching door. They come in standard white but he does custom colors but takes longer. I went with the smaller pedestals which are 9.25" high. (I had to because the others were around 12.5" off floor and it had me up higher than my windshield.) The idea behind this setup is to distribute the load in a wider area instead of a what say 9" or maybe 10" round circular aluminum mount at base. In my opinion the mounting of these seats are a proper joke and I doubted the integrity of the way they are mounted so I took the pedestal route which I plan to simply lagbolt down into floor. (of course sealing all of the proper length stainless steel lagbolts carefully so as not to drill through something below. (be very careful) The pedestals are basically square shaped roughly 16x17" giving you a lot better,stronger seat platform to bolt up to. I don't know your specific needs for height but it is best to keep it as low as possible. I will bet my bottom dollar you stand up most of the time when driving the boat anyways! I measured the top height of windshield first thing to see where I would end up with Wise WD013 pilot seats. (waiting for them at the moment) I think with the padding in the seat,the locking swivel, and the padded seat I should be around 14 to 15 " off of deck. The lower you are the stronger it is! However, this might not work for your specific need. I have an 18 foot fish and ski with a 20 inch high windshield. You can also mount a short pole onto the top of pedestal like a riser but he does not guarantee if you do it. Maybe reinforce if you were to do this. Anyway, best of luck Tom