We may end up moving it again soon---a spot might open up, closer to an outside electrical outlet.
For now, I'm getting the flashing closed up. There is flashing on the underside of the joists. This thin galvanized steel is to keep water and bugs out of our insulation in the floor. But, there were some gaps in it, where they trimmed it away to attach the stabilizing jacks. Looking down and outward, you can see grass through the 1/2in crack:
So, I've cut sheets of flashing to slip around the jack mount--to make the hole smaller. The 2 inches closest to my body are only temporarily folded under. Once in place, I will bend them back so there is a hole only where the jack is.
Here I am sliding it in around the jack, under the jack mount: