i also had HVAC mystery issues in my first duplex when we house hacked it.Regarding the Daikin Mini Split - I have one in the 3rd story of my current home and it seems to work great for us. 

In addition, his point of view is that any attorney worth their salt can find a way to defeat an LLC, they aren’t the rock solid wall people think they are by a long shot.Again, this is what I was told, so please find the answers from an actual attorney.

I am closing 4 deals next week for my rock star land flipper.. 

My opinion on this is split between two answers:1) invest in your backyard.

An agreement would be signed, and the property would be sold in 5 years and proceeds split up appropriately.

@Charles Evans, definitely keep all paperwork associated with your tenant (lease, receipts, etc).For expenses that are not split per unit but are for the entire structure (utilities if not separately metered, mortgage interest, etc), keep a record of those payments so your tax pro can deduct a percentage of them for the unit you're renting.

Equity Partner (Joint Venture): You find & manage the flip, they fund it—split profits 50/50.

@Matthew Cook I would NOT pay for the renovations unless I was on title or had a very formal contract written about the split of profits.

My agent is saying that we are unable to split the contract that way (or reduce the purchase price), so I'm trying to figure out options.

Seems interesting run a split test see if it works out for you.