Ken,
Tractors run in the furrow with plows for one reason...to keep the lateral line of draft a straight line containing the hitch point the center of pull and the center of load....if you can find a way to make a single 10" or 12" bottom pull clean and straight, at depth, in an on-land hitch I'll run one too, but that's a tall order. You would have to hitch a single bottom at least one full plow width left of the center of pull...the bottom would want to cant and ride the landside out of the furrow. The on-land hitch was designed to CORRECT a hitching problem with ever widening multi-bottom plows...on-land hitches for a single bottom would CREATE hitching/performance problems. You can't take all of the shanks off of the left side of a chisel plow, leave the right side shanks on and go out into a field and expect it to pull straight OR do a good job...I don't think a 10" or 12" Brinly plow bottom is going to fare much better.
2 bottoms might be ok with an on-land hitch geometry wise, BUT.....IMHO....these machines flat out don't have enough lead in their a$$es to pull 2 10" bottoms at depth (6") in mixed soil types. Weight them till the cows come home and you are still under weight and traction limited, especially by the small rim diameter of GT tires.......AND, if you can get it heavy enough to hook it, you'll more than likely tear up the rear end, overheat the hydro (you can do that easy enough now), slip the clutch, etc.
The mounted design of the Brinly plows is perfectly acceptable for their intended use and even bean field use IF you can keep the trash from dragging on the sleeve hitch adapter (where 90% of choke-ups start) and CUT the trash that is there so it won't hang on the shin. The line of draft in the Brinly plow (behind a Cub Cadet) is very good in both the vertical and horizontal planes and their only real hold up is a the need for just a little bit more clearance...something the 3pt. plows have and notice they don't have all of the plugging problems.
We are at an implement weight (penetration) and trash clearance disadvantage with sleeve hitch Brinly plows....there isn't a geometery problem with the basic layout, and I can't see how adding one in the form of an on-land hitch is going to help.