Ken, Steve, etc- I like the payloader concept... but if I were to do it, I'd totally reconfigure the hood, fuel tank, etc., so that the sit-height was much lower, and I'd end up changing the axle caster (the opposite direction) so it doesn't steer jerky (like Deer Jerky?). But I'd still end up with a more serious front (now rear) axle, and a serious counterweight. Side-stability could be aided with dual wheels, but not much better. The unfortunate aspect of the payloader-layout, is that you LOOSE the best counterweights- wheel weights, fluid, that big iron transaxle, and my lard-arse holding it down... all on the wrong end. What USED to be 750lbs 36" from the fulcrum, now becomes 200lbs (engine, grille, and a few weights) 20" from the fulcrum.
But I'd still be limited by the axles- now the REAR axle (which is under shear and torque)... is carrying the load, and the front axle, although loaded lighter, gets pounded against the ground when rolling down the street with a counterweight. It's a catch-22. In any realm, the lifting capacity and stability of the Cub Cadet is limited by the fact that it's a small machine... it's got a small peripheral footprint, and doesn't weigh much, so lifting anything very high puts it in a challenge-for-stability... single or double-arm, it ain't very big... even the F-Cub (even in one-arm config) suffers similar bane, but it had much more mass and footprint to enhance stability... and all the weight in the world, and the biggest footprint, will still yield a loader that can become unstable. I could put my buddy's D420 on it's head just as easy as Loader-Mutt, perhaps easier, 'cause it's articulated- the load and footprint (hence load stability) changes with steering angle... steer it wrong with a heavy bucket of weet dirt, and it'll flop like a landlocked catfish.
At the time, my biggest concern was economics and time (cheap, fast, good- pick any two!). I wanted to get something together that I could use for little projects around the lot, and a couple-hundred pounds' capacity was fine. To solve the sink-in and hole-bumping issues, I went to oversized tires, and to make it convenient to operate, I went power-steering and full-foot control.
Next time, I'll build a payloader, use TWO IHCC rears, articulate the bugger, heck, mebbie I'll yank the Volvo from the diesel-project and put it in the Payloader, and put a Wisconsin V4 in the diesel-project... or mebbie I should just buy a payloader and save myself the effort... 'course... a Payloader won't fit in the places I want to go, it'll sink in where I want to float, and it'll cost a whole lot more'n I've got invested in Loader-Mutt...