how has everyone held down their dash's
is it best to just slap some glue on?

Ive got a grp dash to go on a grp body, thinking of putting a thin sheet of ali there to strengthen it. Glue buttered and sandwich made?

Don't you want to ever take it off? Why not use small bolts and washers (button head look good).

I used small stainless rounded over cap head bolts every 100 mm. My gauges also clamp the dash and grp below together. Also put small u trim round the top edge.