Laptop gaming is just never going to be at the same place as desktop gaming. SLI for laptops is more of a gimmick than anything, creating more heat and more issues for negligible gains in performance.
Get a solid performing 870m or 880m laptop with a good 17" screen. Don't worry about spending top-of-the-line dollars on a laptop because no laptop, no matter which boutique you get it from, can have performance enough to justify that kind of spending. The processors, the power, and the GPUs just can't put out the same horsepower a desktop can due to physical limitations like size and heat dissipation.
If you save $1,000 now for not falling for gimmicks, in two year's time that $1,000 can be, with careful savings, enough to purchase a...