From what I have read, if you can mark the corners on the GPS, then use it to walk the line between those two points, it should work. GPS's are very good at differential measurements, as opposed to locating the points/corners/lines solely from the satellites.
Just a tip on buying a GPS, and I hope this is OK with the powers that be, as I have no business connection with this place... There is an online GPS place,
www.thegpsstore.com
They happen to run out of NC, and have a brick-and-mortar store at Ocean Isle Beach. Big selection, and unlike many of the box stores, they actually have batteries in them (or will get them in it). And,they know their stuff and can actually answer questions. Worth taking a look hands-on if you ever get down that way.
First time there, they didn't know me from Adam, but let me take a couple outside (one at a time) to try out. (I wanted to see how it performed in sunlight -- some work better than others in the sun, and I wear super-duper polarized prescription sunglasses that blank out some LCD's, but not others.
