I recall a bloke driving similarly close to the back of my Series 1 Landrover (at 40-ish, not 2 mph!) so I asked my pal in the back to open the tailgate and invite him in. He did.
You've never seen anyone back off quite so quickly. Most effective.
On the rear end of one of the trailers I hauled to Italy and back had a metal plate that read in 1" high lettering "If you can read this prepare to meet they doom", whether anyone ever did I never felt it !