I know this sounds silly, but do you have a major truck stop in your area, like a Love's or a Roady's? A lot of long haul truck drivers have boosters and powered external antennas in their trucks. Do you remember the old Nokia cell phone? The ones that are still on the shelf today for some reason? Those are still around because they all have an external antenna port already built in and the truck drivers love them. Anyhow, if you go to the electronic center in one of those truck stops they should be able to hook you up with a premium system. I think Call Capture or Digital Antenna made the really good ones, but don't remember. Most of these units are all under $500 and are generally a couple hundred bucks.
Now if you really want to get crazy, you get what I have at my cabin, a Cellphone Mate 2020. I had zero service at my cabin and needed emergency cell service. I think the Cellphone Mate system cost me a little over $1,200 to get installed, but everyone within 1,000 yards of me now has service, including the Forest Service District Building. I think it is just a another repeater system, but am not sure. I do know that it is dual band and pretty much all phones work on it.