As much fun as this looks, I am pretty happy with my garment steamer and bag. Despite 60min of steaming.
This is very minor on the scale of internet microwave crimes. That said it isn't exactly the safest idea (fire hazard, plasma balls, arcing etc.) Cancer? Maybe. I once heard a japanese student was patenting a steel forge/furnace that used 6 old magnetotrons from microwaves.
You could use a fine mesh of metal approx 1 foot away from hole to act as faraday cage, to catch any stray waves.
On the plus side, internet might be spotty whenever you use it. Makes a good jammer.