Laminated up some 5/8" thick GB44s and extended the wheelbase 1.5".

Then I took it out to a local parking garage for some testing.

Not bad. A bit more rigid than I anticipated.
Very solid.
I may recess the trucks a bit, get some RII 180s with 42 degree base plates and go with a 70mm wheel in order to lower the deck height a bit.
I just can't seen to get .5" Baltic birch that is stiff enough anymore.