Yes, the 42QD is a bath and a half, and we have two macerator toilets. Our 51 gallon black water tank is the first thing to fill up when boondocking, not only because there's two electric toilets, but because the half bath's sink also drains into the black tank. I'm not sure where the kitchen sink drains, but it's so close to the half bath's sink that it might also drain into the B/W tank.
Our 105 gallon grey water tank rarely has more than 30 or 40 gallons in it - even after several days of boondocking. The grey tank capacity in later model Tours was reduced to 71 gallons, but that should be adequate. I wish I could reverse the black and grey tank capacities in our coach, but since that would be a plumbing nightmare, I think I'm going to put in a dump valve and just tie the two tanks together.
FWIW, when our daughter camped with us (she's in college now) we found our 90 gallon fresh water tank to be barely adequate for a week of boondocking. When it's just Cyndi and I, 90 gallons is fine. In later models, Winnie reduced the fresh water tank's capacity to 85 gallons, so it may be more of an issue for you, depending on how you camp. I ended up installing a second 25 gallon fresh water tank, which has really helped us extend our boondocking trips.
Kev