@FJmaine have you actually put your tank in the tub and seen how well the fuel tank cover fits over the top? For me, it fit enough to bolt it down on 3 of the 4 sides. I ended up having to trim off the passenger side tab of the tank cover because it didn’t reach the door jam ledge. Annoying but not the end of the world.
On a side note, modify the OEM Tran tunnel to fit the Aqualu. You’ll thank me later.
Right now, I have to use the 9/16" mounts that came with the Aqualu tub on top of the Daystar body mounts in order to have clearance over the cross bar. I placed the tank in to see how it fits and it rocks on some thing. I haven't dug into it too far to see what the interference is yet, but I figure that it will clear everything when I put some padding under the tank.
I measured the vertical face of the tank well and got 2 3/8".