Lots of new foster kittens! Advice needed for enclosures

I am taking in 8 foster kittens tomorrow! This is only my second litter but I am very cat and kitten experienced and only working part time right now with lots of flexibility. We are getting 3 five week olds. We’ve been told they are litter trained and eating wet food now, they’ve been in their current foster home for 3 weeks being bottle fed. We also have two more litters of two that are around 6-8 weeks that have also been in their current home at least a week. Then we have one 4-5 month old that has been in the foster home for 5 weeks. We’re helping the rescue out and picking them up on our way home from a trip tomorrow and driving them 7 hours. They are reportedly all healthy.

Their current foster mom said the 4-5 month old has had no contact with any of the little ones but she is desperate for a companion and she thinks she’d be very gentle with them. She just introduced all the little ones today and the 5 week old ones seemed a bit scared of the 6-8 week olds. I have a small play pen and two large ones and a large bedroom to keep them all in. Do you think it’s reasonable to put the 5 week olds in the smaller play pen, the 6-8 week olds in a larger one and the 4-5 month old in a larger one? We’ll be taking them out throughout the day to play in the bedroom and hoping to get them all integrated together.