Yes, that is what I was thinking: harvest a few extra seeds from extra tomatoes throughout the 'season', rather than drying a whole batch out at once...

Save seeds from the first tomato to ripen seeds, mark that plant with a string or a label stuck next to it, then mark the other plants as they set seeds.
I already have a piece of wool tied around the flower-stem of my rogue white California poppy so that I can remember to segregate its seed-pods separately :-)