I called them and they actually quit making them.
Thats too bad, they are/were a good tripod setup.
I have one, and know several others who do as well, but i dont think any would be for sale.
If you have the desire to have a good tripod setup you can actually build a better one, and i have done that.
But i hired a very good machinist to do it for me, all i did was supply a suitable military tripod and a blank check. lol
I know another guy who even built the tripod, and i can email pics to you if your interested.
There will be weak points attached to pretty much all of the store bought systems.
The advantage to building your own is you get to design it as to eliminate the weak points.
But there is no quick, easy, and cheap solution.
Actually, you can build a bench that you can stand up to shoot from as well, and that would be easier and less expensive to build.
We prefer kneeling on the ground rather than sitting on something when using our bench, because its easier to move your body if necessary.
And, the lower the better as for stability of the bench.
When elevating the bench high enough to stand next to, its best to add some type of a leg brace to eliminate wobble.