Just a quick update. I finally found a bigger tractor that fits my needs at a reasonable price. I bought a one owner 2003 Kubota B2710 HST with about 800 hours. It's just the right size, 27HP 4cyl, with a Curtis cab and heat. It doesn't look much different than my little 18HP 3cyl but I'm sure the added engine power will be sufficient for my needs. Even though it's not much different than what I have now I'm excited like a little kid with a new toy. I'm picking it up this week and can't wait to try it out!
After the cold we had this winter I realized I could not operate a tractor in that cold without a cab and heater.