Pre booking will not be necessary. You will get any number of recommendations here, I'd take them all in, look at websites, then vist them on day-one and look over their dive boats and, if you're going to rent gear, have a look at their stuff.
In terms of your concerns about the need for supervision... All operations, pretty much so anywhere you go, are going to put one "DM" in the water with you. Do not assume any standard of care with this person who is better referred to internationally as a "dive guide". If you are lucky, he will be an "underwater naturalist" and will possess great skill at finding stuff. Most do not possess plastic cards proclaiming them as Dive Masters, but they will all likely have skills far advanced from and beyond the abilities of their US "card carrying" counterparts. Still, do not expect an actual Instructor level experience, nor someone who will provide watchful mothering...they might, they might not.
Their main task task is beginning and ending the dive with equal numbers of participants. In between, they point at anything that might amaze or amuse, ranging from rocks to Sea Horses. Now, the very cool thing you can buy very cheaply, especially in the Bay Islands, is your own private DM who will dedicate his time to you and you alone.
Most people thinking they are in need of special care will eventually not hire a private DM, in precisely the same ratio as dive operators that assure guests that their staff DM will handle all of those extra duties as part of their job, no worries. Most guests just decide to "believe" versus spending even an extra $50/day split between "the new kids".
You may be asking which West End/West Bay dive ops utilize small boats which then guarantee a low DM to diver ratio.
All of them.