The ceiling joists will not be strong enough to put additional weight on.

I worked mostly with middle aged clients who struggled with general health and weight loss.

We pay a monthly fee (about $300) to the condo association for upkeep of all the common grounds, roof repairs, maintenance of the parking lot (was recently resurfaced), pressure cleaning of the outside.

I had a listing with Chinese Sheet Rock and when I would lean against the wall, it would bow under my weight (I am not a big person).

A good property manager with solid vendors is literally worth their weight in gold! 

Paying a proficient short sale negotiator is worth it's weight in gold to increase the chances of a short sale being completed efficiently and in keeping a strong line of communication with all parties.

However, after some brain training, the positivity and encouragement presented will carry much more weight than the negative. 

My understanding is that you cannot simply throw tile onto a shingle roof without reinforcing the trusses or roof framing for the added weight. 

I think if you looked at your balance sheet you've already more than dipped your toes :)  You may not have generated massive cash flow but depending on when you bought - the Keys, Brickell, Miami and any land out west suitable for a summer home have appreciated massively and probably shifted your asset/liability balance more than 99% of cash flow investors working at real estate.So another option feeds right into this without having to go with a management weighted DST or syndication. 

You'll also want to ensure you have a good property manager to look after the upkeep of the property if you are not there to notice anything deteriorating or which may need attention.This article goes into a lot of the considerations about whether to form an LLC or not: https://www.mmpph.com/wp-content/uploads/2019/04/May-2019-newsletter.pdfCreating an LLC in California would cost you a minimum tax of $800 every year.