For me acetone was of no help at all. I did use some goo gone, and it did make it a little easier, but until I started using the oscillating tool, I was going nowhere. With the flexible blade, I was able to get down to clean white fiberglass, removing not only the turf but the adhesive residue as well. Obviously that's not really required, but I felt like my new expensive seadek would adhere better to a fresh surface. As far as heat goes, I was careful with it. I'm sure there's a "too much", but I never had any trouble as far as the fiberglass goes. What CAN happen is overheating the hydroturf when you're pulling it away. If you do that, the hydroturf will just tear and you'll have to start over. That not a big deal, but once you get going on a piece, it gets easier the more you remove, so keeping it intact as long as possible seems to help.What I did was get a corner started, and then apply heat to the backside of the hydroturf as I was pulling upwards with one hand and using the oscillator on the edge that meets the fibergalss. Slow and steady. Having a helper to either pull the hyrdroturf or apply the heat was VERY helpful. As far as the oscillator goes, you can play with the speed and angle of the tool to see what works best. Obviously you want a shallow angle on the blade so you won't be damaging the fiberglass underneath. The blade is flexible though, so you really have to be digging to cause a problem. Also, any minor scuffs or anything will be covered by the new seadek anyway, so just pay extra attention to the edges where a mistake might be exposed. Links below for the blade I used. Once you get the old stuff removed, make sure you rinse the deck for a while if you use any acetone/goo gone etc. You don't want that stuff attacking your new seadek.
This is the one that worked best for me. I have a dremel oscillating tool and when I got this blade I realized it actually didn't fit. I had to snip a channel in the back of it before it would slide on my tool, but once I did that it was fine. You can see the difference compared to the blade below, where the back is open. Takes 5 seconds to remedy if needed, but just be aware of it.
https://www.amazon.com/gp/product/B0146WQ6RS/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
I ordered these as well, which fit directly on my dremel. They worked fine too, but the wider blade in the link above was easier/faster.
https://www.amazon.com/gp/product/B00FRMZV9G/ref=oh_aui_detailpage_o00_s01?ie=UTF8&psc=1
You will probably see ridgid scrapers also instead of flexible. I ordered one of those and you definitely want to stay away from that. Much to aggressive on the fiberglass.