I remember wrestling around with those straps for a while when I had my tank out, but my tank is the the original tank. I haven’t had any experience with aftermarket tanks. Maybe they are shaped just a little different? I just made sure all my lines and connections were out of the way of getting crushed and used a floor jack to get it in place.
I had the same issue. I ended up getting longer bolts. Driver's side, you can't permanently install the longer bolt as it bottoms out on the body, but I used it to cinch one strap down, then used the longer bolt on the other side to get it all the way down. I then replaced the bottomed-out longer bolt with the original .
The original bolts are M10 x 1.5 x 35mm long. 35MM is max for the driver's side (maybe 40mm) but you can get a longer bolt for the pass side
make sure your wires and hoses and such aren't being pinched up there. I've seen it a few times when it wouldn't go on, because there was something in between the hump and the body.