Nothing beats local knowledge, or having friends with local knowledge :lol:
I tend to swap overlays with friends in the area, and check with them on a regular basis that nothing has been downgraded or TRO'd. Wayfinder helps but you (allegedly) need to beware certain user groups posting misleading information regarding classification. The only way to be sure is to go to the ROW office armed with Wayfinder data and an OS map/Memory Map to compare it with their definitive map.