The neighborhood is quiet and charming and I assume the investor wanting to buy the vacant lot will most likely either hold for a while or build on it soon.

If you are doing it with dump trucks or vans that hold all your electrician gear then that is easy to prove.

I've been considering building or converting a garage into these units, for a long-term, buy & hold real estate strategy.

Never hold a house that has no payment attached to it.

Not factoring in the fact that I already purchased the current house and lot for more than I should have.I’m looking at modular homes which are supposed to hold their value.

Think about buying and holding, wholesaling, or fix-and-flip strategies.

Though, this process will be the same for the other state (if you created a CA LLC you may need to register it as a foreign LLC in the state in which you are doing business/holding property).

In California you can hold a loan originator endorsement under the DRE.

I am planning to hold the property for next 10 years and I am looking for future appreciation and future low mortgage rate to earn money on this.

I recommend talking with a hard money lender to see what you can qualify for and be able to use those number for your holding costs.