
Car boots are very much not a general purpose storage solution. Chess event venues are public knowledge do if people also know that the cars in those events are liable to contain multiple complete sets of baggage - and pricy, easy to flog etc mobiles - you've definitely got a major risk.
I had my 'baggage' with me several times at Div 3/3N last time round. Wouldn't have been at all convenient to store it the times I did. Probably wouldn't have played to be honest. Not at all surprised it isn't that noticeable in the hall - not like you need a big/visible suitcase for a weekend playing chess!
Actually I can't think why baggage is an issue? It isn't like you're going to be picking it up to take it to the toilet with you

If you're worried about it containing computers transmitting stuff, well anyone setting that up could do it from a remote location almost as easily. Bags in the hall isn't perfectly secure but its actually one of the saner solutions for letting people store stuff like mobiles etc.