I have done the job two times in the last 10 years to two different boats. First one, a 31ft old sailboat, with a scraper took a while and had pain in my neck and back for weeks afterwards. The second one was my Bavaria 32. I paid for glassblasting. The contractor made a shelter around the boat and cleaned everything afterwards. Ok, so it was more expensive, but I didn't need to use a mask and work for hours on the boat.
But to the orginal question. Don't use any heat on the antifouling, it is dangerous enough as it is.