I’m not really into air mattress at burn. My experience has led me to sleeping on the ground as they get deflated by temperature difference and just also getting holes. My recommendation is to bring some form of foam roll or normal camping roll type / inflatable bed setup.

Check this out: Simmons BeautySleep Siesta Memory Foam Mattress: Roll-Up Bed/Flo... https://www.amazon.com/dp/B00FLCFI68/ref=cm_sw_r_sms_awdb_t1_PZOyBb9AA5734

Or maybe a cot Check this out: REDCAMP Camping Cots for Adults, Easy and Portable Folding Cot B... https://www.amazon.com/dp/B0732Z3YF2/ref=cm_sw_r_sms_awdb_t1_m2OyBbF661F64

Also bring a normal sheet or a shower curtain to put on your bedding while out as it will save your bed from the dust.

6 deg c bag should be fine. It almost never freezes should be ok..