extending my outdoor wireless capability

2 acres is a lot to cover. it'd take multiple extenders. 

You get better range outdoors but only if its open.

Even if its not, if you're trying to cover to much distance, such as running from your home to a bard 200-300ft away, a point to point system like airbridge is better than trying to do it with extenders. 

If it was me? I'd be going the route of using Orbi and wiring in as many access points as you need to provide the coverage. 

running standard extenders is going to give you speed and latency issues. Reason why is a standard extender has to recieve and retransmit using the same chip. And it can't do both at once. So right off the start you're throughput is 50% less than what you were at the router and you have an increase in latency. Add in distance and you'll be less than that 50%. Then if you're using another extender cut that speed in half and add even more latency. Orbi avoids that by giving you the option of a hardwired backhaul as well as the tri-band setups use a dedicated router----satellite wirelss backhaul to keep the speeds up and latency down. 

And as much as I like the mesh extenders, they're great if you have 1. If you need more than 1, you should transition to orbi/a full mesh system so you have something controlling/managing the system/band steering. 

Plus running orbi, it gives you the option of outdoor extenders as well. 

You didn't put how far the barn/back area is away but you might even need a combination of orbi/point to point system for coverage. Again, not sure as I'm not there but if its really 2 acres, thats a lot of area to cover.