They have the demap program and had the private land tags for a year or two.I haven't heard of law enforcement problems with this so maybe specific tags would work.I went to the pgc site to ask if they ever considered this but the site is down.
If I remember right some landowners had problems with private land tags causing some of them to post their land.I guess that's why they discontinued it.
Anybody that attempts to pull a stunt on SGL's is nuts because around here it gets patrolled pretty good.