There is no doubt to my mind that you have been quite thorough.

And I definitely understand your concerns.

Perhaps I can offer a fresh perspective that will hopefully be helpful.

While it is clear that you do not have any standing water on your property, my first thought is – what about the surrounding areas?

Are there any nearby neighbors with ponds, etc.?

After investigating these questions, it is important to note that most mosquitoes remain within a half mile of their breeding site, but some can fly many miles.

At any rate, it is imperative to find out where the mosquitoes are originating.

Considering everything you have tried so far, burning citronella oil torches or candles seems basic but I’m going to mention them anyway.

According to Donald Lewis of the Department of Entomology at Iowa State University, citrosa, lemon thyme or citronella grass may help repel mosquitoes, but you have to crush the leaves and rub them on your skin to make them work.

Citronella oil may be more effective at repelling mosquitoes than the plant itself.

It seems that research indicates that the oil in these plants is the repellant when worn or released by humans – not just the plant itself.

I do not know the particulars of the ordinances in your town and would not recommend this solely for insect control – but my backyard chickens eat an amazing number of mosquitoes.

If you are at all interested in outdoor bird pets, guinea fowl are small, cute, and can be personable.

Below is a link with additional information about backyard guinea fowl.

https://extension.umaine.edu/livestock/poultry/guinea-fowl/

I agree that contacting a local mosquito control company is a last resort.

And it likely will not help if the mosquitoes are originating from outside of your own property.