Hi Wayne,
I always balance my plane from upright, out of convenience more than anything else. Flying electric, the location of the batteries is pretty much going to dictate everything on the balance so installing the battery tray is the last thing I do after everything else is finished. I normally do a lot of research on the plane I'm building and rely on the reports of others who have already built the model I'm working on. A quick search on RC universe will usually turn up numerous reports of where the CG should be for any given plane.

Let's say the recommended location is at the leading edge of the wing tube. I install a servo screw into the lite ply root rib immediately above and in line with the leading edge of the wing tube and screw it in so there's just enough room to slide on a piece of nylon coated rudder cable. I do this on each panel and slide the wings on wing tube to where I can just slide the rudder cable over the screws. The nylon cable itself is attached to a 1" diameter piece of wooden dowel about 6 or so inches long that I use as a handle. The ends of the cable each have a crimped loop that I put on the servo screws in the root ribs.

Then I place the batteries in the fuse about where I think they'll need to be to balance the plane which is usually right over the landing gear mount. Then I slide the canopy in position and lift the plane by the handle. The balance will be immediately obvious by the nose or tail dropping. I keep tweaking the battery location until neither the nose nor tail drops and mark the location of the batteries in the fuse. Then I install the battery tray with some adjustment room available in case I want to adjust the CG after my trim flights. Once the tray is glued in, I re-install the batteries on the tray and double check the balance.

After that, I remove the screws from the root ribs and do my final CG tweaks based on flight trim. By starting off with the CG real close to where it needs to be, you can avoid any nasty surprises on your first flight. Hope my explanation makes sense.

Verne Koester