RayV wrote:
I want to thicken up the top with something that will give the bench a
lot of mass, I want this bench to be HEAVY.

Then don't screw around.

Laminate some 1x3 nominal maple on edge with epoxy and 3/8-16 all
thread and fender washers for internal take ups.

Don't even give TiteBond a thought. It is not in the same league with
epoxy.

When finished, head to the top shop and run it thru the drum sander
just enough to get flat surfaces.

It will be a heavy sucker, make sure your vehicle springs are up to
the task.

I have one of these waiting to be cut to size and fitted on the boat
someday.

Lew