Most long term parks require tenants to fully skirt their RV (so look for skirted units) and most tenants who really are staying long term will build a deck or patio, install a storage shed, create a garden, and show other evidence that they have made this their permanent home.  

@Frank ZondloYou will need to have a business that generates ordinary income for you to take advantage of the Solo401K.If you have your own business - what does it do?

Additions, on old multifamilyWe're buying a property that is in an R3 zoned space and it's advertised as 5 units but it appears like some are converted garage or converted patio or something like that. 

I have a feeling I have to share his with you.Generally, there are two tax rates:1) ordinary - higher rate.2 capital gain - max 20%.

Consult with a professional who understands tax implications for foreign investors; In terms of US, few things to consider: since you will generate an active income - which is ordinary, you will need to choose entity that will save you taxes; consider how much income you expect to generate in a first few years; the state; for example with CA you have additional entity level taxes - for example tax on LLC starts at 800 per year even if you have no activity.

As @Steve Vaughan pointed out, full costs for utilities, lawn upkeep, and snow removal are easily offloaded to the tenant, and if things go crazy on the small lawns the fixer landlord can step in with his equipment and save the day before the municipality gets on his back.It's an affordable way for people with ordinary incomes to get into REI.

If we were to sell this property in 2019 we are under the impression that you will not owe capital gains on the profit if your taxable ordinary income is less than $77,200....?

Tenants can't be charged for ordinary wear and tear.

We are looking to re-do enclosed patio 22’x13’ and then adding 22’x22’ second story above that.

Tree removal, shrubs/plants, deck/patio, seed/fertilizer, mulch, driveway replace/seal and misc.The snow caught me again… I had no idea what was hiding under it and unlike the roof… meh.