Renewing this thread over 2 months later...
J2Rentals -- so what machines did you go with and did you eventually get a track machine?
For rental companies, there is a set of tracks that can attach to a wheeled system. That is, tires come off and tracks hook up to the axels. Not as good as a true track system, but better then the steel wrap arounds. Perhaps your already familar with them(?) A rental co in NC got one a few yrs ago.
My recommendation for your tires would be to foam them or go solid rubber (or honecombed). As they tend to find every nail or sharp rock on a job-site. ... but others here may have had a different experience