Stay with balancing your high winger upright like that, it's the best way. Low wingers would usually be done inverted.

Lead shot? Maybe for Skeet or trap shooters but hunters use steel to avoid lead poisoning.

Preliminary balancing is best done with everything installed except the covering. Gives good access to locations for installing balance weight as needed. Properly installed film coverings (Monokote, etc) won't upset the balance very much and will usually require minimal additional weight.