I'll help you a bit with the micro niches under voyeur or voyeurism.
xray
see through
infrared IR
http://www.xrayhunter.com/index2.php
candid nude beach
candid topless beach
candid bikini
http://www.nudebeachmovies.com/index2.php
http://www.bikinivoyeur.com/index2.php
Upskirts
hidden cam upskirt (ie shoe cam, briefcase cam, etc etc)
candid sitting upskirt
party upskirts
http://www.partygirlupskirts.com/index2.php to me this last one is more (exhibitionism) but this industry has adopted or blended alot of these micro niches together wrongly
street candid
candid cameltoe
candid down blouse
Nip Slips
Hidden cams
dressing/changing room
bathroom
shower
locker room
hotel room
hidden wife cam
sleeping wife/gf