The power beyond on my 4300 has an extension on the fill tube. Not sure if the current kit has the same setup, since the one on my 2000 4300 was transfered from my 1998 4200.
Another thing of which you need to be aware is that when you use the power beyond, you divert the flow of hydraulic pressure from your three point hitch to the implement that you power.
Using a backhoe, this isn't an issue since you won't need the three point hitch.
With a wood splitter, the return line is routed back to the three point so that both the splitter and the three point will function.
With a post driver (mine is a Shaver HD8) routing the return line to the three point isn't an option. I mounted a manual diverter valve (about $45.00 from
Surplus Center) on the post driver. After I have positioned the tractor and driver, I switch the diverter valve and drive the post. When I'm done driving the post, I switch the diverter back to the three point hitch circuit.
The return line from the post driver is routed directly back to the hydraulic fill, using a fitting that my dealer supplied when I bought the post driver. The fitting has the same threads as the fill plug. With the extension on the fill, there is ample room to reach the fill without the power beyond mounting hardware getting in the way.
If you can do without the loader, you could certainly run a line from the dual selective control valve back to the post driver and save the expense of the power beyond. I don't think that it would be practical to leave the loader on the tractor and switch hoses every time that you want to move the tractor, but if you removed the loader and left the driver hooked up it should be workable.