Gel coat is typically the outer smooth layer on fiberglass (which obviously doesn't rust). There's no need, nor advantage to removing gel coat prior to any refinishing operation.
Do you perhaps mean "clear coat" (a thin layer of shiny, clear paint), or something else?
Clear coat can be removed by sanding. If you have a lot to do, look into a dual action sander and start with about 120 grit paper. IMO, if your goal is just to extend the life of the car (and you aren't trying for a concours finish), you can stop sanding as soon as you get to intact substrate material (of any sort, metal, primer, base coat, or clear coat). You then prep and finish according to what you have and the manufacturer's instructions.
If you want to remove it entirely, soda blasting is probably faster than sanding the whole car, but I wouldn't go that route if your only goal is to get back to something that you can spray and drive for a while. There are DIY soda blasting setups, but to strip paint, you want to farm that out, IMO.