@James Freeman Since you need a 4 bedroom, I would recommend that you look into the possibility of building an ADU, Accessory Dwelling Unit, to help supplement your current income.

HVAC codes are supplemental to the IRC.

Would the lender allow the buyer to have supplemental loans up to 75% LTV?

I supplement my possibly-too-frequent indoor habit with passions for travel, food, hiking, snowboarding, and live music.I discovered BP through a friend who mentioned his desire to start investing in real estate away from the west coast.

Anyone in the same boat (great day job but looking for that supplemental income/investing potential) have any tips on how, what, when to start and get the ball rolling?

Or, they just want to supplement their income with real estate.Many investors can get 30+% IRRs in their real estate portfolios but that does not hold a candle to the 100% return from their 401k matches. 

The duplex you own - you said it does not cash flow, but supplements your expenses?

Transitioning into our real estate biz, along with supplementation from investment properties would be ideal by the timeframe given would be ideal, but might be too aggressive.

I'm sure you appreciate that he's taking good care of the house and doing small improvements, but as you said your costs are going up and you shouldn't be expected to supplement his living there.  

You can wait to refi and save some cash-flow to supplement the refi money for the next deal if you need to.