Remade the valve holder (from 1-1/2" x 1-1/2" x 1/8" 6061-T6) after flatening the handles. Now it takes up less room and weighs less. Have .25" of red neoprene under the valvel and that isolated the assembly when clamped down.
Tested the actuation at the angle it will be in the fuselage. With a T-handle it feels like a two finger pull to engage.