Thumb with single action cylinder

Have been investigating the method to have a thumb on the Service Port hydraulics on a Kubota mini (U17). Service Port valve has no relief, no passage back to the sump when in neutral, no load check....just a valve that sends fluid to the load and allows a return flow to the sump. Works great for a hammer. Works OK for the tilt bucket cause the tilt bucket is built strong enough to tolerate the full system pressure.

Dont want a damaged/bent/cracked dipper, or, a bent thumb / bent ram...

Thumb with single action cylinder