Show we just save up a down payment once we clear our debt and go the FHA first time home buyer route ?

If you are "broke" as you say and can't afford top dollar, he will just move onto another investor or better yet a retail buyer who is looking to live there.

Buyer Beware!!!

Are there any other types of buyer due diligence that you do on MH that you wouldn't typically do for a stick built home?

Potential risks - incomplete foreclosure.Yes you can buy a property at the tax sale in Jackson County - but to sell it be prepared to find a buyer that will take defective title as that is the only way most title companies will close - some sort of CYA document stating it was acquired via tax sale and might not be 100% clean. 

LBP is nothing to be afraid of and simply needs to be disclosed to the tenant or buyer that the property  was built prior to 1978 and may contain LBP.

Conventional systems will typically cost less than $20,000, but if an Advantec or other specially designed system is needed costs can reach or exceed $30,000".See Cesspools and the Rhode Island Cesspool Act Frequently Asked Questions and The RI Cesspool Act Goes into Effect 1/1/16: What Buyers & Sellers Need to Know (from which the quote above was taken).You will want to check with your mortgage broker, however, with whether the bank will have a problem with a repair credit that large.

I get what the builder is saying... they WILL find another buyer who doesn't care. 

The only reason we'd like to be renting is to go back into the market as a cash buyer rather than subject to the sale of the current home and so we're not rushed into a purchase.

This strategy is difficult to do even more difficult considering an out of state buyer.