What I’d like to accomplish is an upgrade in home (space, location, etc) without putting myself in a bad financial position.

I upgraded to Unlimited Plus a few months after use when it was still $5/month.

This will allow you to get to know the property, its maintenance items, and slowly tenant proof(upgrade) the units before you move back to CA.

If you proceed with upgrading the panel add enough capacity to charge an electric car and put in baseboard heaters so you wont' have to do this again if you decide to add either of those options down the road. 

I’ve had a turn over of 4 units which has allowed for upgrades and renovations.

Aside from possibly replacing items that upgrade your property value for 3+ years (appliances, countertops, etc) I would not offer any kind of upgrade.

electrical upgrades , plumbing,kitchen, roofing, shower, sewer,windows, doors, appliances.. plus I add the first 6month on the loan.My concern is that $18k as leftover in the escrow it should go back to the principal and I only  got  $15K the bank said that the rest is towards mortgage payments… ??? 

.- Maintenance & Repairs: act quickly on any request, use the opportunity to upgrade, set expectations for the common areas.

You may have to upgrade your membership to use it.2.

Oregon is also an increasingly popular retirement destination, for primary and second home buyers that don't need to have STR permissions, the options and areas to invest are robust, and there is even high demand for upgraded and updated furnished mid term rentals to help off set operating costs.