From your post's heading, I thought you were towing a Buick from your dinghy.
I too, would only go by what my owner's manual stipulates....and by-pass switches are easy to install. On my GMC, I only have to pull one fuse, and a simple switch now takes care of that chore.
However, pulling the fuse for the battery may indeed cause you to not have power for your BB and you may have to run an axillary line from your mh's battery.
Good luck
Ron