Any suggestions on invisible fence system? Obviously the wireless would be easier but most of them say 1/2 acre which is not much. I have 4 acres and would like for dogs to be able to use the majority of it.

I had one around an acre and it worked well, but I don't know how it would do on an area that size. Other than buying a system with a couple of extra rolls of wire and laying it out around the area and testing it I don't know where you could find out, just put the collar around your neck and walk into the perimeter and see if it works.

ive paid Invisible Fence for one, and ive bought one from Lowes and done it myself.

I would not do it myself again. Pizza roller cuts through wet grass pretty easy though, and then used a paint stir stick to poke the wire down

I had one many years ago for my 2 dachshunds, the female ended up getting out and ran over and killed, the male was so scared of it I only put his collar on him about once a week. I installed it myself using a gas powered edger, the edger made a nice miniature trench for the wire. I crossed my driveway at an expansion joint and covered the wire with caulk. I did loose my controller once to a lightning strike, they are prone to that.

I put in a sport dog brand one around almost 4 acres. It wasn’t that bad. I went to sunbelt rentals rented a walk behind cable trencher/layer. Did it all in an long afternoon. Works great. I had to cross an asphalt driveway. I used a demo concrete saw to cut a gap in it the took a black caulk to fill in. My only advice would be to do it when there is some moisture in the soil.
https://www.sunbeltrentals.com/equipment/detail/1151/0700035/4in-trencher-cable-installer/

I had Dog Guard installed. They use a larger gauge wire than others I looked at and cost less than the others. My lab knows where the boundary is and have not had an escape in 3 years.

My buddy had a really headstrong male lab. Wife didnt want the look of a fence in the back yard so he installed one and i remember asking him how he liked it and how it worked for him. He said that all it did was let him know when his dog left the yard and when he returned. He'd yelp when he crossed it heading out and he'd yelp when he crossed it coming back. LOL

The new generation invisible fence will shock them until the battery wears out if they go out. My WFO lab obeys it and has only broken it when the collar battery died and I didn't know it.

While wide open, he is trainable though.

I had one for my Brittany several years ago. She would test it by easing in until it beeped and then back off. One day my power went off for several hours and I never saw her again.