I have seen where it was difficult to get to 2 rod caps to unscrew the bolts, but never 4. Cirtain tools will get to them. Now, take all the main caps off, use a long stick like broom handle and knock the 4 pistons loose from the bottom up. You dont have to get them out quite yet. Then take a pry bar and start lifting on the crank. Up and down up and down. The stuck piston will give it up sooner or later. keep trying to twist the crank too. Could just be 1 wrist pin stuck in the piston.