I tend to lean toward BigBellyBBQ's last post. Sharing a kitchen may not be a good idea. However, if you decide it is something that you want to try then work up a business plan first. (it is very important and prudent to be detailed in your business plan as it is your best "crystal ball" regarding the success of your proposed business)
I would start my research, for a Business plan, with these points.
1) What type of access will you have to the kitchen, full or partial (time/equipment,etc)? (important for evaluating your cooking/serving process)
2) How will your supplies be purchased, stored, managed, inventoried? (important to be able to track yours separate from his)
3) What type of food does he currently sell? Will it compete for your BBQ receipts? If so what percent of total sales do you estimate will be yours? (important to calculate your projected Gross Sales)
4) How will sales be documented, your food and his? Is there an electronic POS system, etc? Will/can it be shared for both your sales and his? (necessary for ascertaining your actual Gross Sales from your product)
5) You mention that he is checking to see if his liability insurance would cover you. This will probably depend on the business arrangement. If you are an employe -Yes. If you are a separate business entity using his facility - could easily be No and you would need to obtain your own.
6) Will you offer any sales other than on premises? i.e. catering, etc This could affect the liability insurance aspect. It can also affect the need for access to the kitchen. You will also need space (at the Station or other location) to store your catering equipment such Cambro hot hold units, tables, etc.
These are just a few but imho are some of the more important points to be addressed.
Following this thread I am inclined to think that you may want to propose a separate business entity (LLC is my preference since a Sole Proprietorship puts all of your personal assets at risk) that would have a lease type agreement that allows you the access required to cook and sell your product out of his establishment using his smoker (a DETAILED lease agreement drawn up by an attorney). Both of you would need to have a "meeting of the minds" on the terms of the lease and it's details. This would allow for business liability protection for you and the LLC would also be a vehicle that can be used if things change in the future should the possibility of "going it on your own" arises.
Of course this is all just my opinion and not intended to be legal advice.