I have a GPS that must be 10 yrs old and I hope they have come a long way to do what you want. Mine will only get me within about 30'+/-. I used it in hunting when tracking. It does very poorly unless you can see the sky fairly well and the faster you move the more accurate it is. To stand at a tree and mark the location mine sure would not do it. On the other hand it would likely give you a basic guide line. You might also want to get a 3D map with a pair of stereo scopes and you should be able to mark that with the info even if it is fairly flat. If totally flat or way too small of an area that would not work either. My suggestion would to get a hand level, some collored ribbon and a sketch pad. Mark each tappable and nearly tapable tree with a robbon and draw a rough sketch of the land, trying to mark each tree and if flat mark each at the same level, then based on the height of the ribbon you can plot your mainline. I used this idea and it worked well in my first bush but I could see the slopes, which were only about 6' rise on the mainline in 400'. From there the laterals at the far end had to be strung and tapped with ladders, with the worst being as high as 13' from the ground. Definately not ideal. If I ever get vac in this bush the taps will be lower and some sap ladders would be in order. This bush is only 180 taps so vac will ba a while. Once I get an RO, vac will then be worth it because I have likely another 200+ taps possible, mostly reds but some silvers. I now only tap about 50 reds that are higher up in elevation. The rest of the reds and silvers would need sap ladders too.
Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.