But the previous owner had made some additions to the house and an extra bedroom and bathroom were added apparently without obtaining a permit.

We haven’t had a bad review because they don’t know how home buying works and nobody gives them the time of day when they have bad credit etc but we go the extra mile to do everything we can to get them qualified and show them that they don’t have to be stuck renting

Make sure to explain the benefits for them as well.Also, it never hurts to reimburse your tenants for the extra water usage. 

Throw in an extra $5,000 and send them on a cruise.Find the need.

We're pretty cheap as far as what we charge for critters compared to our competition, but this helps offset the extra cleaning required for pets and profits us for being flexible. 

I guess I don't feel the need to try and get that extra $100.

So it's not at all usual.I had a 3BR SFR, with a 4th extra room and had rented to 3 single people in the past.

When it goes well, there is nothing that says you can't just pay them extra money as a way of saying thank you.

Add another 75 in parts and maybe an extra hour for retro fitting.

My advice: just pay the extra 1%-1.5% rate and get a commercial loan on 20 years.