Locations for checkpoints will vary according to what the local gendarmes are looking for. Drunks & drugs are one thing. Restricting movement is another. Learn where they will be in your area. Nobody's gonna post any information usefull on a large scale as it will be good only for their individual AO.
As a general rule one should have alternate routes to get where ever you need to be by not using limited access highways & state roads. Learn to take advantage or allyways, large parking lots, unpaved roads, gated fire roads, snowmobile trails & backyards (if need be). The last will attract attention so that's a last resort.
As far as the gated trail question goes; You do have a gas powered circular saw in your BOV, right ?