Not sure if I saw this idea somewhere and just absorbed it, and reused it, But as far as I'm aware I haven't.
All you need is Sprue!
(And a dozer blade, I rescued mine from a badly painted
IG tank, still need to strip it.)
Just cut some lengths of sprue, preferably you can find a long enough piece with no mold flashing or offshoots, but its just a simple process of filing them flat if you cant.
Using the sprue cut the length you need to reach the front of your tank and cut some shorter ones and place them underneath the tank in the middle or anywhere it wont be visible when placed on the table.
Using the tapered sides you will be making a taperlock, (commonly known as a dovetail) to hold the longer pieces on termporarily
Glue, and voila!
If you are very careful with your glue, glue the first piece down, then place your second piece down and glue the third one in, while firmly holding them constantly be moving the longer piece so that it doesnt get glued down aswell and will be a perfect fit.
I have only done this on a rhino, but its very liable to be used to hold many other things, and on many other vehicles
Edit : make sure to let the first holding piece dry first, makes it easier to glue down the other one.
And the finished result, added a crossbeam to support it. You cannot see how it is held on, so works great.