Save yourself alot of work on the out rigger idea, use a set of Bigfoot levelers and just carry large pads for real soft ground. You will be rock solid stable.
Check with Jason at Big Foot on placement. On both of mine conversions the front jacks where located just behind the fuel tanks up front (on this rig they are slightly staggered). On the back they are just behind the rear wheels. (Single axle)
2012 Showhauler 28'6" Motorhome on a Columbia w/ 450 Mercedes.