The mesh network routers will do what you need. Eero is one for example. You can easily blanket your whole compound with WiFi.

In the interest of full disclosure, I work for Bosch Security and I used to own an IT company. I do a lot of security systems and a lot of wireless for video. I have recommended Ubiquiti wireless products to my dealers and found it to be very reliable, secure and fast. I recommend their Nano stations for a high speed point to point wireless. Make sure you enable AES 256 bit Encryption. I have had systems up and running for over 5 years with no downtime. Most of my applications are a bit more mission critical than your barn and this works very well. You will find their products very cost effective. If your looking for camera recommendations, take a look at the Bosch NBE-6502-AL and the NIN-73023-A3AS. These are starlight cameras and have very good analytics that can alarm when a person steps on your property. We sell them for high end residential and the DOD. On a side note the analytics integrate with our alarm panels so you can trip an alarm when someone comes on your property. A couple of tips, don't use mesh with video, use point to point or point to multipoint it is more reliable and way faster. I'm on your side of the state often, I can help with the system design if your interested.