To close out this thread...I decided to go with Check or Stay Chains whatever term is appropriate...
Picture #1 is of upper bracket secured to part of under frame that actually supports ROPS..
Picture #2 is of same bracket but different angle for detail... Bolt is 3/8 inch grade Grade 8...
Picture #3 is of a 5/16 inch "U" bolt (from cable clamp) anchoring lower part of chain to Quick Hitch, decided to make chains universal to anything on QH...
Picture #4 is another detail of lower anchor, again its a 5/16 "U" bolt from cable clamp. In center of QH I used a rod coupler cut down to where it just fit between side of QH and threaded one side of "U" bolt into it and tighten it as a nut, them put another 5/16 bolt in to coupler from outside of QH in effort to transfer some of the load to outer side of QH and hopefully not distort it to much under strain/usage...
Quick links ( 1/4 inch) are rated to not exceed 880 pounds so I think they will do... If i have any failures I will upgrade to stouter quick links and chains or whatever hardware necessary.... Remember this on a SCUT and probably highest load on QH may be about 500 pounds (rotary mower?)
Thanks for looking, and any comments welcome...
Dale