The lowest part of the bilge on the Commander is reachable from floorboard # 3, right behind where the bilge drops away. Its a little difficult to work there.

Its been suggested that you could mount the bilge pump and float switch next to eachother on a small board, maybe one of those small plastic kitchen cutting boards. That would make installation easier. You could also pull the unit out a bit for cleaning and servicing.

I'm thinking of trying that, but I would want to make sure the whole unit couldn't overturn somehow.

The bilge pump wouldn't be on the very bottom of the bilge. But, bilge pumps aren't effective for getting the very last of the water out of the bilge anyway.

You're taking the right approach by preventing water from leaking into the boat in the first place.

I've never been able to achieve a truly dry and dusty bilge, even after hunting down any deck leaks. A little water will get in through the cowl vent at the bow. Also, a small amount can get in around the hatchboards in a driving rain. I won't be happy until I have cobwebs in my bilge.

A few coats of epoxy or bilgecoat paint on the bottom of the bilge is a good idea too. Whenever I do epoxy work, I prepare a section of bilge so I can smeer the excess epoxy down there.