letscook, the tomato sauce is not going to eat away at the aluminum if the lasagna is in the freezer. I agree that storing tomato sauce in aluminum would be a bad idea under other circumstances. In this case though, the pan of lasagna goes directly from freezer to oven and doesn't have time to etch through the aluminum pan.
ctyler, I repeat, you are all good. I've done this many many times for potlucks and large gatherings I needed to prep for. Enjoy your party and tell us how the lasagna went over.
You're only given a little spark of madness. You mustn't lose it. Robin Williams