[eryque]

"Acceptable" depends one exactly what the goal is. If you need something accurate, no, though you'll be close. If you just need a ballpark figure, then yes.

If you want accuracy, do what Fuzzy says so the volume pot won't affect the measurement. You will, however, have the tone pot in parallel, which will affect the measurement. So if you want to be really accurate, take a few extra seconds to unsolder the connections for the hot leads.