I’d love to get this group’s thoughts on what to do with 3 acres of undeveloped land (no septic, no water) in the Texas Hill Country that I plan to eventually pass on to my children (read: never sell because it’s family land).

Never go under water.

really the only thing in common with them is the homes are Mobile.MHP much easier to manage day to day.RV park lots of management issues also with RV the chems in the RV's are strong and it can affect how you deal with Grey water and sewage.. many RV parks though turn into MHP if the authorities just let the RVS stay and never move..

The next night, while at the property to let the tenants know I was the new owner, I noticed he was in the community laundry and with his phone plugged, a bottle of piss on the floor, and looked like he was going to sleep in there.

Properties, for novices, which look good on paper and have good cash flow usually come with C to D+ areas, risky tenants, and a lot of cap ex that you can't see on the internet (basements, roofs, water issues, outdated mechanicals).You are turning a terrible loss into a springboard which is great, but you are trying to move too quickly it sounds like.

Do you have insurance for your appliances, if the tenant says the washer stopped draining the water and now their clothes smell like mildew, do you know how to schedule service with warranty or call an appliance tech?

Like do some cleaning job, contacting maintenance people, knowing how to pay water bills etc. these are all the basic work when you become a landlord and you need to know how to manage your property first.

Near outdoor activities, good food and some kind of water.

If the house still has 60 amp service that tells me its old , so the water line is probaly old . 

I feel like those kind of fixes can be estimated when getting a house inspected and appraised. knowing when a new water heater was put in or when a roof was replaced, these all have life expectancies and yes accidents happen but if this is happening on a regular basis for you, like I said, I have concerns.