Which motor did you get? Even an electric start can be pulled in a pinch. There's a notch in the flywheel for such. In a OMC, anyway. My battery died last summer and left me in a bad spot. I did manage to pull the 40 OMC over using a spare rope ( which I ALWAYS carry) and the notch on the flywheel. It wasn't difficult. However extenuating circumstances made for a much longer story than I'm prepared to write, right now.
Since then I carry 2 when venturing far from civilization. I use a gel cell wheelchair battery for a spare, in a wheelchair box. When I'm home it powers my my kid's toy Jeep. If tipped or rolled it won't leak electrolyte.
Here's a pic of both.
and just the main battery
The horizontal bungie is supposed to keep the hooks of the battery bungie away from the tube, however I don't trust it entirely and have been stuffing an old life cushion between the battery box and pontoon for added insurance. I had a bungie hook abrade the pontoon on my old boat and don't want to see that happen again.
Good luck, Safe boating!