Just a thought. What about 4 wheels on legs that pivot up and down and lock into place? Drop the wheels and move it, then raise them back up when its in place. That would allow larger tires for the rough terrain.
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If you have a Harbor Freight near you or a Northern Tools wheels/tires can be had cheap.
http://www.harborfreight.com/10-inch-pneumatic-tire-30900.html
http://www.northerntool.com/shop/tools/category_tires-wheels+low-speed-pneumatic-tires-wheels+low-speed-wheels
I can think of about 223 solutions to that predator problem. The City has just about caught up with me but 15 years back when I built this house it was country. Yote problem was so bad that I started keeping a rifle by the front door. I cleared out 17 yotes the first year from my front porch...
Looks like you are doing a fair job of it by yourself. With that said why not hold off on finishing it until the MIL has had enough of living with livestock and moves? :)
1, 2, 3. Its too hard to eat somebody that you are on a first name basis with.Any critter that might be on the table down the road only gets a number around here.