first of all don't worry about freaking her out. you paid for filming and she's an experienced porn girl. it'll be fine lol.
i'm an amateur who didn't know anything about the science of video/photography, so obviously grain of salt. what i offer is trial and error practical observations after a lot of filming. i'm made some great footage and some disappointing ones with girls who were so game but i never saw again so i can film better lol! it's really such an underdiscussed topic for people who want to get the most out of their filming without the massive camera investment.
firstly, don't use a gopro. i know it's popular because it's relatively inexpensive and durable, but it makes terrible close up pov footage. it looks fine if that's all you have, but seriously, compare and use your high end phone and gopro side by side. the gopro's indoor and close performance are terrible. it's really for outdoor, natural light, open views, and ofc action sports/activities. the field of view isn't much better than a phone, and it won't look sharp - if you're used to how porn videos look where every detail of body parts is clear, the gopro will fall way short. it's not built for indoor lighting, so everything will look super dark or oversaturated in color. you will need to flood the room like a porn shoot to get good detail pickup. the widest setting fisheyes (can be corrected in software) and doesn't add nearly enough vertical view to be worth the trouble. look up gopro footage on pornhub or the previews on our old friend bareseeder's site. it looks like ass even though it's 4k.
for free, an iphone or high end android will make great videos. shoot at 4k then convert them down to 1080p or lower later to save space. the flashlight will kinda wash out the colors because you only get one super bright brightness but it's more than tolerable. if you want to buy something get one of those ring light handles that hold your phone inside so you have a nice handle and brightness settings. another simple cheap handy gadget is a selfie stick that can double as a small tripod. it'll give you a grip to hold on to pov and you can put the feet out and set it on the nightstand when you want to put it down. one more piece of advice is don't use the wide angle lens (the digital zoom out) for any phone in case you're thinking of the fov advantages. wide angle will look really grainy compared to the regular camera at 1.0x because the wide angle camera is never as good as the main so use the main at 1.0x and adjust your distance instead.
there are a few cameras around $500-1k that will give you better footage. they're usually higher end vlogging cameras. the point and shoots that cost a few hundred will not be better than your phone. over that and you're dealing with dslrs and pro cameras. you're on your own there lol.
