Young Aspiring Racer near Oshkosh Wisconsin with Little Knowled

Follow the advice already given to you in your other thread.

Go spectate at races ($30 gives you unlimited weekend entry and ability to paddock-walk and talk to teams and also demonstrates you can get to a track on your own and are interested enough to show up). Doesn't have to be Lemons. Take a day trip to your local tracks (brainerd, road america, joliet/autobahn).

Learn how to wrench on cars (either fixing your own track day car, or even taking a local program). Start fixing friends cars.

Start doing HPDEs with your BMW 3-series (or other car) to show that you've at least been on a race track in real life.

Find your local SCCA or other car club and get involved in autocross. Saying you "don't have access to anything in real life" demonstrates how little research you've done. Most people don't live next to race tracks. Some teams tow over 12 hours each way for events.

Start saving money. And don't be afraid to wait two years (things become easier when you're 18).

Save up and get your full safety gear so at least you can help with fueling if someone takes you on as crew.

This new mindset is nice to see in contrast to prior posts.. you're on the right track.

Contrary to popular belief, Lemons is expensive, has some incredible drivers, and some of the best wrenchers/engineers I've ever met. Compared to [that other series]... Lemons has a much wider range of experience and talent, but on the higher end of that spectrum, the drivers are better, the wrenchers are better, and actual engineering is invested into the vehicles than just throwing money at them. All of this is to say that I would be careful about overpromising your experience and capabilities, most of the more experienced guys will see right through it.

What makes you appealing is your eagerness, willingness to learn, youth, and energy. Be careful about overselling yourself... ability to drive a manual, experience with SIM racing, and ability to sustain high G's without passing out (FYI, unless you have underlying health problems, G-forces experienced during a budget enduro race are nowhere near black out territory) are not relevant selling points. Are you willing to help clean the shop? Do you mind vacuuming out the rat poop at the start of a new build? Are you willing to run crew for the first few races before becoming a driver? I think most of us around your age cut our teeth into the automotive world by sweeping floors, organizing shops, and changing oil. We love having new people in the community, and the best way for you to be appealing would be to have a mentality more along the lines of "hey, I can do basic car stuff, no job is too big or small for me, and I want to help you." I don't know of any teams that would be willing to "sponsor" you... no money, no drivey. However, there may be a team willing to take you in as crew that can provide their experience and knowledge in exchange for your time.

Volunteering to crew for teams would be a great start and a good way to learn. Holding lights while someone works lets you see up close what folks are doing (if you pay attention); changing tires, brakes, and oil are easy and allow more experienced mechanics to do more trouble-shooting; and even the sweeping floors in the shop/making gas runs during the race/cleaning windows/fetch tools/load & unload the truck & trailer/other miscellaneous chores will be appreciated by a team as you learn and help with more involved maintenance. 

I would pay the entry fee (and feed them all weekend) for any person who is interested enough to volunteer to work at a race.  If you bring a tent and sleeping bag, then you have a free weekend at the race with a terrific opportunity to learn and make connections.  Anyone who crewed for us would get to drive some during practice day (where allowed by the track) and would be first in line to drive when we had an open seat. We are a bit too far south for you (about a 14-15 hour drive to the airshow when I go), but I'm sure you could find a team in your area that would do the same.