If you do not feel comfortable pursuing additional growth, I'd wait it out just a bit. 

Get out of your comfort zone.

Are there any challenges I might face, especially if my long-term tenants aren’t comfortable with the short-term rental activity in the same building?

Whether that's mobile home parks or any other kind of commercially valuated endeavor is a matter of personal comfort and preference.

Get out of your comfort zone.

There's a lot more compliance, regulations, and other protections that many brokers do not feel comfortable hiring just anyone. 

It’s better to have less rooms and to have them large enough to comfortably fit a queen bed.

Whether it's gathering around the tree, sharing laughter over a meal, or watching the magic in your loved ones’ eyes, there’s nothing like the comfort of being home for the holidays.Merry Christmas from my family to yours!

I hadn’t thought about the risk of expanding my portfolio by having multiple properties over leveraged, although that seems to be a growth strategy that many use,  I’m not sure it’s one I’m comfortable with.  

However, consider STR seasonality, local regulations, and management demands, and ensure your equity loan and new primary residence costs fit comfortably within your budget.