By previous threads, I figure you mean like:
https://ogrforum.ogaugerr.com/...69#81819042996642969
I think you'll find it easier to find the 3-position momentary DPDT switch (spring-loaded return-to-center) than a 2-position momentary DPST switch. So you'd only throw the DPDT switch in the UNLOAD direction and ignore the other switch direction.