For AA 6061 sheet, see page 3-264 of
MMPDS-01. Be sure to verify the AMS specification to make sure you've got the right material for these tables.
AA 6063 is not a typical aircraft alloy—it's quite weak. (Actually, neither is AA 6061, but at least it's a fair bit stronger.)
AA 7075 (page 3-371) and AA 2024 (page 3-71) are more common high-strength aircraft alloys.
As for electrical isolation, maybe a paint or conformal coating? Epoxy-based, perhaps?