Mike: I think you've misunderstood the purpose of a hitch lock.
It is only for security use when the van is parked up.
Most of them have heavy duty plastic weatherproof covers which just need a sponge over.
On any reputable make, it is impossible to tow with the hitchlock attached anyway, as the locking plate goes where the towball is.
They are like all anti-theft deterrents, another reason to make the would be thief look for easier pickings.
There is nothing quite like that 'empty' feeling when you discover that your van isn't where you left it!!