I’d stay away from a large amount of Warren county for buy and hold, mostly septic and oil heat which would be a nightmare (oil heat is expensive and septic I wouldn’t trust with just any tenant).

My intention is to not initially increase the rent, make some improvements to the efficiency of their HVAC systems (go from ancient oil to high-efficiency gas) and, once I have the work done, increase the rent to compensate.

I'd go with an oil based or shellac and use a respirator.

Both have submetered electric and one has individual thermostat controlled electric heaters in each unit.The major expenses that the landlord pays for between the two properties include:Common oil boiler (10 yrs old) feeding steam system ($9k/year oil bill) in one property - does anyone have experience with gas conversion/replacement and submetering with a steam system?  

Is there a living room and kitchen or are they sitting on couches on the back yard and cooking on a BBQ?!

Although in JP, it's entirely possible that the fuel is oil, not gas.  

(Think about how buying a pre-cooked rotisserie chicken in the deli is more expensive than buying a raw chicken and some spices and doing it yourself.)

Cook County, Lake County, and DuPage seem to be affected the most.

Here's what the wholesaler is laying out:No seller or wholesaler disclosure on the property … it's an as-is saleOne open house will be held at which the property can be viewedBuyers have 24 hours after the end of the open house to make an offer comprising simply the offer amount along with proof of fundsWholesaler selects the winning bid that night and send the buyer an assignment contract.Buyer wires a deposit (over $10k, and not called earnest money but called a deposit) to wholesaler's attorney the next morningWholesaler sends the contract between seller & wholesaler to the buyer and/or buyer's attorney1 calendar day for attorney's review (in NJ real estate contracts are not binding until both party's attorneys agree on the contract)Deposit is only refundable if title is not clearApprox 3 weeks to closeThere's no underground oil tank contingency (in NJ it's common to have the seller remove an underground storage tank).Are these steps & conditions & timing typical for a wholesale deal in NJ?

I also  noticed  my tenants  have cooking ware , such as rice cooker, induction heat top in their room.