I have seen guys doing that to their own rigs. One approach is to get a huge combine or similiar tire and cut the sidewalls out of it to make a rubber track and then loop it over your rear tires and then rig up an old trailer axle under the tractor as an idler with the ability tension it with threaded rod or the like. That guy used steel tracks and it looks like the idler has some suspension to it. Cool
If I had a two wheel drive rig I might consider doing something similair.
Way back when, a US company by the name of ARPS built a half-track system just like that. They ended up on N Fords and TO Fergusons quite often. I'll try to find a link to an ARPS tracked Ford or Fergie.