I don't think WiFi is going to work here. I know there are some outdoor WiFi extenders but I have heard mostly negative things about them. You could also try a WiFi booster but you are going to run into the same problem more than likely. Another option could be coax cable and use MoCA, but that will require you to dig a ditch from one cabin to the next. Assuming the land is owned by both parties and no one else you should be able to dig a ditch and lay the coax cable from one property to the next.
https://www.screenbeam.com/wifihelp/wifibooster/what-is-moca-why-do-i-want-it/