This would be from the same carpet company I used when I fixed up the house, so not trying to gouge them or anything.I'm looking for some guidance in this situation, pitfalls I could run into, or just straight up illegality.

In order to better protect everyone in the transaction - I have a real estate license too- so I am held to a higher standard by the state.  

Just understand that there are two sides to these transactions.

HELOCs are specifically helpful in this case so long as you are consistent with paying it back in a timely manner for the next transaction.

I would say my end goals would be some financial independence and also some business knowledge through transactions.

I already have a Stessa account which can be connected with a bank account and has the benefits of collecting rent and keeping track of documents, receipts and transactions.

for double closing you would need your funds to buy then sell it to end buyer at premium. there are transactional funding companies that can lend the cash for a fee.

I can tell you at our Phoenix branch every single employee loves what they do and take an immense amount of pride and accountability in every transaction.

That is the worst black hole in my opinion in the transaction. 

Additionally, the ability to schedule the construction loan origination at the same time as the land settlement saves a lot of time not dealing with transactional inefficiencies.