Your clarification is interesting. So you aren't planning on this being a real source of income, more a fun "food jam" for like-minded chefs/cooks? Well, you ought to be able to handle that pretty simply. I get the idea of just wanting to "one off" something every four months to try out some stuff you normally don't get to try.
If you already have a terrestrial kitchen then you are already insured (likely with some coverage for off site catering, if not, get it) and certified. So the "underground" aspect is really only extended to some of the food you want to serve? Well, tread carefully. Especially with regards to two aspects:
1)alcohol. Unpasturized dairy is one thing, booze turns you into a bootlegger and in Canada you would be looking way more than a fine. You could do time, you could loose your legit business. I would not go there!
2) Just because something is "edgy" doesn't mean its good. If you come across a small producer who is making a limited run of an amazing unpasteurized cheese, well, that might be a risk you want to take (I can't speak to your mind set there). But if you become determined to serve raw cheese and then go searching for one to fill that column, that is wrong headed.
If you try something like this do it as above board as possible. Invites are one thing but I suspect you might be surprised at how limited your uptake will be. Even then, if you want to expand your personal brand as you imply, you will need web and social media presence. If you can secure enough RSVPs from blind invites alone, odds are these will be people who already know you, so your are preaching to the converted only. No social capitol is gained. You want people who unfamiliar with your work. You will need a wider net. And that will push you "above ground." Again, that is where you want to be. You can't be hush-hush about something and expect it to boost your profile or create buzz. Have you ever seen a resume with "Voted Best Meth Dealer, 2011" on it? And, if I, as a restaurant chef, saw a resume from somebody who has been skirting the rules I had to follow to undercut my business, well, guess where that resume would be filed...
The tickets idea is a solid one and one I strongly recommend. PayPal, Eventbright, are great solutions for managing this sort of thing. And open up credit card sales for advance purchases. If you think that doesn't matter, you need a rethink.
Now, "underground" is a potential for marketing. You can sell the aura of a culinary speakeasy while being a safe and insured environment. The thing you have to think about is, will the market for "edgy" be a demographic that can pay. And pay for a food experience. If you are pre-booking than you are pretty much looking at sit down, fine dining experience. Either a long form menu that would double as the night's entertainment. Or a three course with a flip. Do you think the wharehouse dance party crowd would be up for a three hour sit down diner? I dunno...
Skip the food truck. You want a van(s). You will likely need table/chair rentals (not to mention plates, cutlery, etc) so you want something to cart that stuff around. Focus on portable cooking pieces (induction burners, circulators, anything that can run on household power). Build a portable "kitchen" setup, it will serve you well over time.