with davrow, hit local tractor repair place, and have them make up a coupe hoses with fittings for quick connects. perhaps a couple swivel or like fittings in the short hoses to make them shorter but also bend easier. (make sure you have enough length of hose to keep you hand/fingers from getting pinched)
i have hit levers over the years on various equipment, and just nothing comes to mind to keep them in a lock position. and i just blame myself for not being aware and just being stupid when it does happen.
if the valves have a "detent" notch on them. see about adjusting the spring/tension if that is even possible. so it is harder to pull/push out of the detent.
hhmsss old allis chalmers has a "half circle" with a grove following the circle edge, were a spring, washers, bolt/nut all come together through handle for rear end. it also has a butter fly nut. so you can twist it down and lock the handle in place to hold a given position for the rear. at most i just tighten the butterfly nut down enough so there is a little bit of force required to move handle. rarely if ever actually tighten the butterfly nut all the way down.
any sort of chain/hook/clamp i can think of to hold it in place. sounds like an accident in my mind waiting to happen. and would be more finkey than just making sure you do not hit lever in first place.