What I'd keep in mind now is not to add more unnecessary debt onto your plate than you can handle.

So, you get all these advantages, but, you avoid the numerous and significant risks of more advanced and complicated strategies like BRRRR'ing, flipping, wholesaling, etc.  

Will affect the allocation of liabilities among partners and thus tax basis.Be aware that what you're proposing -- having members coming and going in an LLC -- might create some complicated scenarios for taxes and increase your tax professional fees. 

Not sure the exact specifics on how to do this, but I'm sure a retirement planner would be able to assist you.Real estate investing has enough tax shelters and advantages as it is, I do not see the need to complicate things by opening a new IRA to do so.

I'm also looking at areas away from my home market, which can complicate the BRRR process.

I'd avoid sophisticated/complicated and expensive structures at this stage, especially if the only reason you need a partner is because you're both undercapitalized. 

Your post includes a lot of extra, unnecessary information, but it sounds like your key issue here is the bank will not qualify you for the loan as your debt to income ratio is to high, partially due to the car loan.They way debt-to-income ratio works is the bank takes your total monthly debt payments and divides it by your total monthly income.

I know that all who invested gets paid if the deal does well, but it got complicated because I don't have money to contribute.

This whole deal is really complicated. 

To complicate things further it’s hard to put a price tag on many of these repairs, whenever there is long term water intrusion you run the risk of “mission creep” i.e. replacing some rotten siding leads to replacing some rotten sheathing leads to realizing the studs are also rotten leads to realizing the foundation looks crappy too now you’re rebuilding everything.