I cut a hole a couple inches in diameter in the floor of my westy so
that the big nut on the propane connection to my Olympian Wave 3 heater
could fit through with a little wiggle room, as the heater is mounted
only about 1/2 inch off the floor.

I used a hole saw I've head for years, I don't think it's a cheap one
but not too expensive either, probably from Sears.

I drilled a 1/4 inch pilot hole, then drilled out the wood floor plug
(it's a Westy) and then stopped and removed the plug. Then I oiled the
bottom of the hole to help with the cutting. You aren't supposed to do
any of this kind of cutting without lubricant.

I did the above step to try to avoid getting oil on the carped fibers,
and it worked though I'm sure some seeped under the floorboard. That's
OK.

The rest was very easy. I borrowed a 3/4 inch drill for the job,
though, as you need lots of torque and the handle extenstions on the
big drill so you can control the drilling and react to all that torque.

After the heater was mounted, I got underneath with stainless steel
scrubber-brush steel wool and with a sharp stick packed it in around
the tubing, filling the hole so no air or varmints could enter the
cabin from underneath.

Jim