Thanks for all the good advice.

I purchased two 4 - inch wheels for the back and a 3 1/2 - inch wheel for the front (I would have bought all 4 inch, but the hobby shop didn't have three in stock - they seem to only sell wheels in pairs for some reason). I looked at the 6 - inch wheels that I originally planned to purchase and started laughing to myself. Those wheels are gigantic. I also used a 11 x 6 prop instead of the 12 x 6.

The wheels made a huge difference. Taxiing was much easier and I didn't fear the prop digging into the dirt. I also felt more confident on the landings knowing that if I came in a little fast and rolled into the really bumpy part of the runway my plane could handle it. I also enjoy the little extra room that the 1/2 inch of the front wheel gives to the back wheels to help insure I land with the rear wheels first.

I didn't like the 11 x 6 prop as much as the 12 x 6. The plane seemed sluggish.