Trailer or motorhome.....once underway....both doors locked for security.
Regular lock and dead bolt. This way if one fails to latch, the other might keep it closed.
Ken and Terry
2018 Sunseeker 2430S with Trekker cap
and only rarely pushed by our 2017 GMC Terrain toad (4 wheels down)
Former Georgetown 330TS owner for 10 years with more mods than I can count.