I would suggest speaking with your condo association's attorney before you pass any new bylaws amending your current condominium bylaws. You want to make sure that any bylaws that you pass are not in violation of the Illinois Condominium Act which would open your condo association up to potential litigation from an owner who was "wronged" by the updated bylaws and rules.
Typically lenders are concerned about the total percentage of units that are rented within any condominium association. In your building's case even one rental brings you to 16.67% rental units. Most lenders underwriting guidelines require that fewer than X percentage of units in any association be rentals. Often that percentage is 20% or less, although underwriting guidelines are constantly adjusted.
You also want to avoid writing rules or bylaws that would allow one (or two) units in the association to become the de facto "rental" units. If you limit the number of rental units to one, then you do not want the first unit to be rented to remain the only unit that can be rented in your development ad infinitum. You want to write rules and bylaws that rotate the ability to rent your unit. If you don't then the one and only unit that can be rented in the development becomes automatically more valuable than the others.
You also do not want to find yourself in a situation where you have additional owners who are in desperate need of renting (i.e. due to a job relocation or some other unforeseen circumstance) who are prohibited from renting their units on even a short term basis.
I'd suggest contacting your association's attorney. Or if your association does not already have an attorney on retainer, I'd suggest contacting John H. Bickley, III at the law offices of Kovitz, Shifrin, Nesbit. His number is 847-537-0500, and this law firm specializes in condominium law. I do have other attorneys who I might suggest, but I would certainly contact this firm first for this type of work. Let me know if you have any additional questions or if you need any additional assistance. Good luck.
Broker Associate, Sudler Sotheby's International Realty