Wifi issues - full timer - Help appreciated

So, I'm going to be living full time in an RV parked outside of my parents house for a few months, and I need to solve this wifi issue because it's driving me crazy. We are parked outside of the house on the opposite side of where the only wired connection is at, so we're about 80-100 feet away from the router that I set up. A wifi app that I have says we're getting about a 50% connection to that router, and the speeds/connection wasn't good at all so we bought an extender. We placed it right under the window on the side of the house we're parked at, so we're only about 15-20 feet away. Everything is in line of site, so even though it's long distances there aren't but one or two walls it's all going through. The connection from the router to the extender is showing 93%, and our connection while in the rv to the extender is about 90%, so we're getting good connections. The issue is that the connection is constantly dropping out, and when it is connected it's extremely laggy. We run the speeds and sometimes it's less than 2mbps, regardless of us getting a great connection. There's no way to run a wired connection to the camper conveniently. We've tried powerline extenders but the power we have running to the camper through the electrical box on the house doesn't seem to carry the connection and we can't get it to work. I've tried every available wifi channel. I've tried tin foil with the antenna to direct the signal. I've tried 5ghz and 2.4ghz. I've tried everything I can think of. We have the amazon firestick and the way it works is it connects to our wifi and somehow sets up a wifi connection from the remote to the stick using the same channel, so I thought that might be causing interference, but we connected that to 5ghz while we connected to 2.4ghz since that'd put it on different channels but it doesn't work any better. It's frustrating to the point where I'm ready to give up, but with the work I do I need internet access. Has anyone ever been in a similar situation and found a good solution? I'm willing to put money into it, but I don't know where to go. I've called the internet company and they said they could run a wire to the camper but they'd have to charge me another monthly fee for having another wired connection, which is crazy. Thanks in advance for any assistance.