need help what to get

i have two questions?
one is in regards to a spot i found where the couple go at it constantly but the lights are always turned off...to make matters worse, since it is a crack between the blinds and the window siding, if i step into the space to see, they will know that someone is there due to light being blocked...(i tell you this business is the riskiest and kudos to those that get footage of windows sex since it's by far the most difficult of all voyeuring)
so is it worth getting an Infra-Red camera to be able to see in pitch dark room with no light at all available?(if so what camera site would you recommend i look at...the smaller the better but i realize IR is going to require power meaning a little bulky)

2) i found a spot where i could only install a camera (very tiny otherwise no) for a bathroom window. i don't have access to the inside of the house. i can only do it outside.... is there a wireless mighty tiny camera that can be activated and deactivated at the same time being positioned directly on a window without being so obvious?

Mate, I can only help with what you shouldn't get...Caught!!!
Good luck.
Cheers

Put something over the crack for a few weeks so they get used to it being dark... then your shadow won't mean anything...