Reason is each category of property , at least to me, has different set of challenges, opportunities and costs so the numbers are different. 

An RV being mobile seems to present additional challenges in this scenario. 

Equity is the meat.It's important to remember that you're either trying to buy equity or cash flow at a discount.A significant challenge of trying to become an investor, in the beginning, is that we become attached to each of the few leads that are generated and try to squeeze every ounce of possibility out a very opportunity.

It's unique in size and structure for the area.How much time and money would it take to get this changed to a legal 4plex, if at all possible?

Their way of being unique in their own way. 

This past week we had some delays and challenges.  

This thread is really reinforcing the challenges of starting out in California.

I think it is because of our unique housing stock.  

But each situation is unique as you know...much depends on market, your skills, budgets, etc..

You may even know exactly what exercises to do and what foods to eat, but the real challenge is an undying motivation and commitment.