Co-sleeping is merely having your child(ren) sleep in your bed or in a bed beside your bed. It is very much AP BUT boundaries still need to be established for it to be functional for EVERY one involved. Meaning the child needs to learn that whether they want to or not they NEED to sleep. Yes, they can wake and seek comfort but that comfort should be something like a quick pat on the back or a 'shh' from the parent not hour long entertainment and rocking etc.
I had one AP family oh man. They were great people but man. The kid was up for 3-4hours in the night every night. Dad would rock her and he would sleep in the chair all night (the kid was over a year old) I remember mom texting me one morning saying they had a rough night but hey managed to get the child to sleep most the night, as long as the child was able to keep her finger in dad's belly button all night. WTF! that is complete and utter control of the child. How is that comfortable for the father. WHY is the child's comfort (aka finger in belly button) above the dads comfort (sleeping at all, and without a finger in his belly button).
Sometimes people you need to close the door and let the child cry themselves to sleep.
I say this as a parent that never left my child to cry it out. I taught her how to sleep and self sooth at an early age so we didn't have to either cry it out OR all be sleep deprived. This meant I didn't start sleep habits that SUCK when the child is older. Sure rock a 2month old to sleep but don't rock your 10month old to sleep because then you have to rock your 18month old to sleep. It takes time and effort and a whole lot of effort but as a parent you sign up for the responsibilities of raising a child. You don't have children so they can control your every move and keep you up for hours every night. Being a parent means saying NO (endlessly), being firm, being mean and being hated (at times) it is in the best interests of our children.
Again, I state this is NOT AP parenting. this is parenting without boundaries and the inability to take control!
I think your option of going home for naps is PERFECT. They created this mess they can deal with it.