when I had a carburated 2 stroke Merc 150 and had to crank it many many times to start it, I probably should have had 2 batteries. Since getting a fuel injected 4 stroke, it starts in half a crank every time.
I don't run an electric trolling motor and I don't use the boat in freezing weather.
My experience is that a single 27DP battery works perfectly.

Hey spare , I never even thought about battery's plus, there's one by me and I'm hoping yo check it out ,thanks I was going yo Wally World they do have starting battery's I think they sell the group 24 for about 62 dollars but it's 625 cca I'm not 100 percent sure on the price but it's in the sixths for sure I'm going to battery's plus 1000 Mca can't beat that

I run two group 24 1000 MCA starting batteries in the V, a single group 24 1000 MCA starting battery in the skiff.

All Interstates, minimal electronics.

If you're near Savannah, River Supply in Thunderbolt has them cheaper than the Interstate distribution center out in Rincon.

They give 16 dollars a piece for your old ones, any size.