I agree with Drak on this one regarding anything regarding the design process.
But since you asked....
Along with other reasons, the Lace Alumitone were specifically designed to reduce weight. IIRC, they weigh about 1/2 of what a "regular" pup weighs, maybe less. With this in mind, I wouldn't worry much about the extra 3oz from the 2nd pickup. You'd never notice the difference. Honestly, I don't believe you'd see an appreciable difference with the weight of the added electronics either.
Why?
The weight of the wood removed for the 2nd pup route will counteract some of the weight of the pup. Likewise with the larger control cavity for the electronics.
Something else to consider for the super-thin is the control cavity itself. You might want to consider top routing it and going with pickguard mounted electronics. If you back-route, you'll lose depth in the c/c with the back plate. It may only be 1/8"-3/16", but you don't have very much to play with back there and it could make the world of difference between using p/p pots (and the N-tune) or not.