Greg,
Sounds great, glad it worked out for you.
About your tires:
Stay away from calcium, it will rot your wheels. And dont fill them above 3/4 full with fluid. The tires still need flexibility, especially if you run the backhoe on it.
This is the stuff that i was told by my dealer that they put in mine
Rim Guard is a liquid tire ballast that maximizes pulling power, improves lifting performance, and reduces the risk of tipping.
www.rimguardsolutions.com
Wheel spacers:
Lots of guys run wheel spacers. If you dont have a mid mount mowing deck, the 2in spacers should work. I`m not a fan of wheel spacers just for the simple reason is that i run the 48in box blade on mine. I dont want the tires out that far. I`d rather keep the tire tracks inside the width of my box blade. Other than that, i have no problem with wheel spacers. They are pricey, so shop around. Some of the guys here can probably tell you the best ones to buy for your money.