My biggest concern with the Rockville sub is it's lack of any waterproofing. I live in the PNW and it can get wet in the cab...I've had a solid half inch of water sloshing around from melted snow before I pulled the drain plugs.
That and when I pull the top come spring...
My sub floats freely on the floor behind the passenger seat. Last year on a trail run we had a wickedly deep river to cross and I had to pull my sub apart and throw it on the front seat so it didn't get submerged, a real pain in the ass to do on the trail.
And same thing...At least once or twice a year I get caught in a bad rain storm and the floors fill with water. One project for me this year is to mount it permanently. I have a tool box in the back and I think I am going to do something similar--use nutserts and mount the sub on the back wall of the tool box with a large rubber isolating mat.