She would be putting all the cash down for the property and I'm a contractor and would take care of all of the rehab work along with finding the house, dealing with real estate agent etc. how can we make it so that it would be 50-50 ownership of the property and all future profit? 

As a first step, I’ll print and read The Ultimate Beginner’s Guide to Real Estate Investing.

I would suggest starting with reading the IRC book all the way through multiple times.

I'm looking to buy a house in the St Pete market & have read zoning regulations, articles about STR (anything less than 30 days) and have discussed with my realtor.  

Quote from @Amy Smith: Be careful you don't get in too deep.

If I donated to aids health foundation and they spent the money on rent control instead of aids research or health care, I would be pissed.  

this means that these owners are under much less pressure to sell, and so they don't really care that their price won't let the property be a good rental. 

Now the situation has occurred that we need to rent the house out in order to help pay for his long term care expenses. 

If you don't care about income and are more of a capital gain kind of guy, prices are already high (as you noticed) and there's plenty of land available to buy so I'm not sure how much is left in the tank.

Coghill they are trying to take care of several things:1) Approval to access credit reportsA video tour of my home office (required by the credit repository to show security, so access to office & computers is limited to avoid data theft)Credit checks on me and my partner (required by the credit repository to make sure you are not criminals looking to steal others' data)Copies of the deeds for every property we own (required by the credit repository to confirm you aren't just self-serving)A copy of my partner’s home lease and utility bills (required by the credit repository to prove his legal address, so they can pursue him criminally if he steals data)Business phone bills (required by the credit repository to prove an actual business)2) Approval to use banking ACH system to accept tenant payments and pay ownersBusiness phone bills (required by banking industry to prove business legitimacy)A signed letter from the bank verifying our accounts (to prove legitimate business banking accounts.