...there was a large market at the time.
Chicago is famous for stunning, college-age brunettes. And steak. And pizza. And hot dogs. And live blues clubs.
I'd start by fining a brunette, then pick the food. After dinner take her to a blues club like Buddy Guys and then back to your room to add more harmony.
Seriously, the work needed to find POT's is the same everywhere. But since you are traveling there, I will offer some counter-intuitive advice: Start looking now to get an idea of the market - but- leave the "Notify her when viewed" setting off.
Next, don't bother contacting a POT until you are less than 3 days from arriving. Even if you can get a POT to agree to a M&G or BCD one or more weeks ahead, she's likely to cancel, ghost, or ask for advance cash (which must be an absolute no).
Set up low-cost M&G's, perhaps with an option to go to a nice dinner or even BCD when it seems appropriate. The last time I was there, I had 3 M&G dinners set with the hope of flipping at least one to BCD. That strategy failed, as all three either wanted a huge allowance, or wanted two more dates before considering BCD. The result: Over $800 spent on 3 dinners and another $6.75 for a bottle of lube at 7-11 to cure my blue balls. Fortunately, I was able to find a local pro through TER who saved me the need to use the lube.
If I had been there more than 3 days, like your 5-6 month trip, I could have greatly improved my results.
Life is good
The Cat