Remove the bolts, carefully, with a small 7/16" wrench. When reinstalling, clamp everything together with a zip tie. Install, tighten most of the way, cut the zip tie and remove, then finish tightening the bolts.
I wouldn't say bubble back exactly but the housing that holds the thermostats are right against the cowling in the rear. I don't know if that answers your question. maybe I should take a pic.
The 88 hp isn't a bubble back. "Bubble back" describes the shape of the rear exhaust plate, yours is flat but higher hp models like the 110 hp had a tuned bubble shaped exhaust plate. Thermostats are even harder to access with a bubble back.
You think a flatback is tough? I did R&R on my 140 recently. My procedure is to use 3M 847 to glue up the casting/gasket/spacer, clamp in vice and let cure. Glue the springs to the poppets as well. Go have a few beers while it cures. Tie a couple pieces of string around the seated poppet/springs to keep them in place, then wrestle the assembly into the motor. It helps to remove the plastic shroud around the leg, remove the two rear pan mount bolts and pry and block the pan down - you get a lot more wrench room.
