With the temp up to 75, I decided today was the day to crawl under the house to take a look at the hole for the bathtub drain. Been having trouble stripping these cheap screwdriver bits on the heavy duty screws that hold the closure for the water heater, so couple of days ago I picked up some construction grade DeWalt driver bits. They did the trick! Got the crawlspace hatch off easily, crawled under the house and put pipe insulation on the water lines, and was happy to discover the hvac ductwork is already insulated. The hole will be easier to fix from inside the linen closet instead of under the house. New bits got the hatch cover back on tight, as well as finishing tightening the water heater door.
I was also happy I didn't bump into any Halloween buggers under the house