A small digital scale could still help, if you don't mind puzzling over a little arithmetic...
It's best for eggs to lose weight steadily, which would mean losing the same percentage each week. Do a bit of research and find out what percentage turkey eggs are supposed to lose over the whole...
I have ne experience of hatching turkey eggs but from your description it sounds like your humidity was too high. For the next hatch you can do what Pawtraitart says, or you could weigh your eggs to gauge moisture loss. That's what I do with my chicken eggs and it works great...