Stray cat we've been feeding has given birth on our back porch! what should we do?!

Blondie started giving birth about 2 hours ago. there are 3 kittens and it seems like there are no more coming. she is in a diy cat shelter that is a styrofoam cooler filled with hay inside of a storage tote filled with hay (she really loves that thing since I put it out a few months ago. I see her in it almost every night that it's below 50°). I would like to bring them inside, but after some googling it looks like that could be a bad idea cuz it'll stress her out. we have 2 indoor cats, but we certainly have an extra room that we can put her and her kittens in if we need to. outside temps are currently about 50° and will reach the 70s soon. she has food and clean water out. I unfortunately cannot bring her to the vet or anything. we did call a vet when we realized she was giving birth and they pretty much just told us to stay calm and give her space to do her thing. Any advice you guys have?

dad is also hanging around and sprayed the cat shelter once she started giving birth. we have a local charity that does free nueter and spays about twice a year, so the next time they do a drive we were gonna try to trap them to get them fixed.

edit: pic of Blondie and her kittens!

edit 2: there are 4 kittens! we've nicknamed them Tangerine (very orange), Peach (more blonde than orange), TJ (he's a tuxedo, just like the dad, Tux and was how we knew who the dad likely was), and Dusty (light gray). we are clearing out a spare bedroom and plan on moving them inside before the temps drop again tonight. we've also gotten kitten food to feed to Mama Blondie. we are currently calling around to see how we can get Tux fixed asap as we wait for Mama Blondie and the kittens to grow

update: I've brought them inside and I have them in my office! I've cleaned out as much as I can to give them space. the transition to bringing them in when pretty smooth, but once Blondie realized she was inside she HISSED pretty hard at me and did scare the crap out of me for a moment. I'm trying to give her some time to settle and adjust. there is food, water, and a litter box. I've set up a camera to keep an eye on them