People are wound very tight nowadays and they quite often are there own worst enemy with these things as they work themselves into a frenzy.
Do I think he is a dodgy bloke... yes
Would I say he was involved in crime... yes, most likely fraud
Do I think there is an organised crime group planning to heist your van off your driveway.... no
As Dave has rightly pointed out, proper thieves are (for the most part) very low sophistication opportunists. The stories of organised crime groups using high tech planning and tactics to steal vehicles is an illusion that people like to use to cover the fact that they quite often have been complacent - leaving keys by doors, leaving car doors unlocked, not having basic CCTV etc.
Are there gangs who target cars to order - yes, however they are not some fast and the furious style, they are usually very poor and low skilled migrants who take their chances with quick thefts. Cars are nearly impossible to ring effectively at any worth while scale nowadays, so they are either stolen for local use, exported or broken down for parts.
Fit a PIR light, get a Ring or some basic CCTV and report pictures (and numbers plates!!) to the Police so that officers can deal with these vehicles when they pop up again.
@Tic tac Hope this helps, I know it's small comfort but I'm speaking with a fair bit of experience here.