Odds are, the owner doesn't have a clue.If the outside temperature is over 90 degrees, A/C is an emergency, and you can pay the repair, and send the PM the bill.

I would figure out how to manage the temperature and then install the flooring that's best suited for the space, noise levels, etc.

Due to humidity and temperature changes the stuff is expanding and contracting pretty badly so I'll be switching brands to something else.

A couple of questions :Did your inspector actually test the units or list the phrase ambient temperature was too high to test ? 

The difference in temperatures between day and night or between summer and winter can produce the effect as well. 

The cost to heat is huge in NJ with minimum heating temperature mandates (I can't remember what they were) for temperature and duration (68 degrees around the clock from Oct. 1 to April 15?).

I don't know what kind of heater this is but electric heat is expensive in our area and poorly functioning units can sometimes draw more energy, if the thermostat on a unit doesn't work or the heater doesn't sense temperature correctly you can have a situation where it is always on drawing electric. 

I'm about to start on a similar project, between the snow and the temperatures, the house challange seems easy.

A simple, low cost method...especially if it is only a problem for a few months out of the year...is window units (for heat or a/c) or baseboard heating, to help supplement the temperature provided by the HVAC.

Use wire nuts inside the junction box to join the new and old cables.You should also buy a new temperature and pressure relief valve (safety valve) for each new heater, if it doesn't come with one in the box.