The cavity may still cause some issues but I would doubt it would be much, you could just layer the MDF on the outside and sand it down to a smooth finsih to apply the veneer to, this way it would be solid and not be an issue at all, except heavier to move around and cost a little more.

Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70