I then went on to use it as a successful income producing property for the next 6 years, bringing in roughly 26-28k a year in annual gross rental income. 

When you make an offer and you have that inspection contingency time, that is a good time to get the GC in there officially with a more detailed estimate based on the scope of work that you would produce for them.I can't urge you enough to read books and study spreadsheets (a bunch of them here on bigger pockets).

Are you trying to (1) defer taxes or (2) find an income producing asset?

From my research a business credit card does not impact your personal credit should I have a high credit utilization rate. 

If you sell you will have $100000 cash to invest.  5% down on $200000 will leave you around $90000 to invest in income producing properties.

Let's also assume there is sufficient demand to fill the park and sell the homes to new or current residents, so it's full.   22 lots producing $250 would give you a gross revenue of $66k.  

Yes, the higher the rent to value ratio, the better, but some of my most reliable cash flow producing props have a ratio lower than 1%.

What you're suggesting would produce better leads and the agent would only have to pay for that lead upon successfully closing the transaction.

Is this the only feasible route to utilize retirement savings?

They'll need to own different types of shares in order to get different returns.How do you need to break down the ownership in order to produce a 17-18% IRR and 10% Cash on cash return for your investors?