Tiny House Sales Pre-Construction Purchase Agreement? HELP!

[Jason Kahle]

I am needing to create a pre-construction purchase agreement... The agreement will be for the purchase of either a tiny house or park model. I have a partnership with a factory that builds these in 9 weeks. I need to collect funds from customer up front for the build to begin or at least half up front. 

This is NOT real estate... These are regulated by the DMV and are RVIA certified units. 

Can anyone connect me with someone who either has a great knowledge of this type of thing or knows someone who might? 

Thanks!