RE: Top-Flite T-34 mentor fuel tank position
The DC-3 uses a split flap, the T-34 does not. The differences in the type of control surface necessitate different construction methods.
Again, the fuel tank was located as it was to clear the retractable gear. Keeping scale looks prevents easy access.
When built dead-stock, to the plans, the wing is plenty strong and doesn't need additional reinforcement. "Glassing" a wing isn't necessary if it's designed not to need it. Adding fiberglass reinforcement will only add weight and not really contribute much.