The houses in this area are going for 350 plus 3 room and 2.5 bathroom with 1400 square feet

I would suggest that you jump into some local meetups, get connected with local investors and real estate agents who can help you on your path to running numbers and getting your feet wet on actually knowing more of a good hard cost for rehabs. 

I would have done a  JV with a partner who is experienced and you would bring the cash and he the experience and the connections to get my feet wet

I like to have what I call the loyalty conversation with them after the first round of seeing properties.  

And if the builders insurance is not current from what  I know there will be no insurance the insurance has to be active when the claim is made  @John Mocker  John i have been going round and round with my insurance guy on this one. 

You can't count on believing that the family member will not produce a handwritten lease (real or not), or other paperwork & tactics, to throw a big old wrench in your initial/expected timeline.You CAN expect that if they see you as the big old rich/developer/bad guy enemy, they will do as much damage as they can, and drag their feet as long as possible.See if you can feel out what the relative actually wants/ needs, connect/come prepared with info on resources for local "housing help" options, etc (perhaps), and figure out what you can do to solve the problem (cash for keys with an incentive for quicker move out timeframe?

A big difference is that their season is year round (and if anything, this is the low season right now) whereas I'm assuming Galveston is a ~6 month season with only 2-3 months of really peak rates.But I agree it's doubtful the properties are cash flowing at current prices/rates. 

There is just so much money to be made from this purchase and i don't want to drag my feet and let the opportunity slide by once someone else realizes the cashflow this place makes, and they buy and and i loose the opportunity.So i guess I'm looking for options for help with down payment.

As for financing tiny homes as defined are under 400 sq. feet in size. 

You're definitely ahead of the curve of most folks that are investing for the "first" time since you've already gotten your feet wet in Mexico City.