This is a fairly common occurrence, except for the fact that the neighbor is not a considerate farmer but the always insane DOT. Normally, I would suggest you simply go to the neighbor and strike a deal to pay them an easement fee or even buy that tiny strip of land (or even do nothing, since you might be able to claim that land under the law of adverse possession), in this case you’ve got a neighbor that is not negotiable, reasonable or compassionate. So I would simply budget to pull those homes a few feet forward to get them off the DOT land. It will be very expensive to do, as you will have to remove the skirting, disconnect the utilities, jack it up, install wheels and axles, move it 4’ forward, and then repeat those steps to hook it back up. On top of that, you’ll have to make sure that you have the room to move each home forward a few feet. Figure on probably $3,000 to $4,000 per home when you get done putting it back together, but you might get a lower bid in volume.