Illegal here in MD. Buddy of mine used to hunt a farm adjacent to a large horse operation. One year he shot a P&Y buck that ended up dead on the neighbor's horse property, who was a real a-hole. After refusing permission for my buddy to retrieve it, the neighbor went and found it himself, took a backhoe and buried the whole deer...meat, hide and the 160ish head. Buddy spoke to DNR, who advised there was nothing to be done about it and the landowner had every right to do what the did. Really sucked but that's the law.
Best to have these things worked out ahead of time. I've made it a point to meet with, exchange numbers, and have an understanding of things worked out with the neighbors on all the pieces I hunt. To me the good feeling of knowing everyone is on the same page and respecting each other would far outweigh that feeling of "sneaking" onto another property. Plus if a deer crosses the line during prime hunting hours, I certainly don't want to go traipsing through someone else's area pursuing it right then and ruining their hunt, as I wouldn't want them doing it to me. Contact them and retrieve it when it works with both sides.