I agree with you on expenses which is why my offer is where it is.

However, I have received an offer on my property from a very good and trustworthy friend that I have agreed to accept.

First good old politicking, find all of the other owners who can vote and see if they will agree to vote with you to allow STR or even to amend the bylays. 

If I sign the mortgage but not the Note, I don't have liability for the debt, but my interest in the property is subordinate to the lien and so can be foreclosed if the debt is not repaid as agreed.

Partnerships make me nervous as for every thing that you can agree on there are 100 things you can be misaligned on. 

Maybe they would even agree to a sale price up front so you can plan for it.

I agree with @Jonathan Greene here that the first step is thinking through what to do with the primary residence - you might try this tool that I built a few months ago to analyze whether you should keep or sell the primary residence! 

I agree some people do leave trash all over instead of putting it in the trash cans.

Reason we are trying this strategy is just due to the fact that just like the rest of the country there is limited supply in this market.

Agree with above.