+1 on the De Oro support. Undoubtedly you can get the perfect angle you're looking for when placed on the right or left leg. It is also virtually indestructible, portable, light, and the suction cups seem more robust than on other supports. Been using mine for years and still looks and functions like new.
I also recently gave the barnett support a try, and the versatility will definitely allow for the one to use it on the right leg as well. If the person doesn't need a high neck angle they can get the short model, but both the standard/short models have nobs to adjust the height.
"Success grants its rewards to a few, but is the dream of the multitudes.
Excellence is available to all, but is accepted only by a few." - Christopher Parkening