How we vac bag veneers is to do the first layer of glass and the veneer at the same time. Spray 3M super77 adhesive to the back of the veneer and roll out 4 oz cloth on it. We then template the fiberglassed veneer and cut it out with shears. A nice trick is to lightly sand the edges of the veneer before putting on the board so the veneer is close to flush with the foam.Then wet up the fiberglass with epoxy resin and tape it to the board with masking tape so it doesn't shift when in the bag. Leave it in the bag for at least an hour so the resin is cured. Then take it out and laminate a layer of 4 oz over it.