Geez, what a horrible situation.
If you are caring for OB pts for the first 30-45min of their stay you will be basically unavailable to the rest of the house for that time. Sometimes you could get away with a 5min run for supplies so long as another unit could hear your bell and would answer it- but some moms cannot be left alone...hmmm.
Is there an OB committee in your hospital that you could attend, let the docs, and officially notify nursing admin about your inability to be in two places at once. Most times other areas of the hospital can muddle through if they know you have an emergency going on elsewhere, but you must respond to codes/traumas so they should know in writing that you may have to leave an unassessed mom in the care of a non-OB nurse in extreme situations.
In an emergency situation you should be prepared to call the code team to help in OB- you acting as traffic director, assigning tasks while maintaining FHT, interpreting the strip and reassuring mom. Even just getting a recorder over to help frees you up to care for the pt. Make sure you have the fixings for a rapid c section prep, IV lines, speculum exams always in each labor room and then make everyone- lab, admitting, anesthesia, come to where you are for signatures, to pick up specimens, ask questions.
You mention having one RN on call- you will need two with that number of scheduled deliveries. We have LPNs in OB, they can do comfort measures for laboring moms, immediate postpartum hygiene and teaching, immediate care of healthy babies, and they can take over completely once you decide that mom and baby are stable postpartum, freeing the RN for the next labor, or allowing her to complete paperwork plus supervision for problems. WE staff with one RN, and one LPN at night, but our LPNs have been with us for years.
Sorry about the long post, but I hope some of this helps. Feel free to PM me if I can answer any more questions.