Thank you Daren and Coachgeo for your replies.
coachgeo, I did find those two links but thanks for posting them. The guage wheel on a rake by gpreuss is quite similar to the design I am trying to replicate. The post with the box scraper/blade had a few nuances that made it better IMHO and those are what I am trying to find.
Daren, your suggestion does give me an idear using two tires instead of one. It would mean obtaining some additional supplies, not a big deal though. I have most of the steel already cut and had planed on using a re purposed tire -swivel and square steel tub from a retired bush hog. I am going to use a top link turnbuckle to do the height adjustment similar to the setup in coachgeo's link for the rake.
The advantage of what I am trying to replicate is that by removing two pins the tire, swivel, square steel tub and the turnbuckle are all removed from the box leaving only four tabs that hold the two pins and two pieces of angle iron welded to the back of the box in the center.
Thanks again for your replies and giving me something to think about.