Sudden Idea... bit weird perhaps, but... perhaps not.
Why not take the aircraft carrier way.
you don't need an nuclear reactor, diesel engine is enough. don't need that high speed of an aircraft carrier, that reduce power plant size.
That is a spectacularly stupid idea. You would be designing an all new ship with none of the advantages of designing an all new ship.
Cleansheet and other commercial craft are right out leaving just the AKE, LPD, & MLP/AFSB options.
Of those, the MLP/AFSB is the slowest - and likely too slow for the operations in question, just leaving the AKE and LPD hulls. I'll go into the breakdowns later when I'm not falling asleep.
To continue, to my knowledge there have been no studies of converting the AKE hull to a hospital ship. While I do like the AKE hull and program (ahead of schedule and under budget!), I'm not sure it's the best option (although I'm sure NASSCO would love to get a contract to study it!).
What has been studied is a conversion of the oldest of the LSDs - The Whidbey Island Class. I know there were two MIT studies (
link and
link)on converting the oldest ships into hospital ships with landing docks. While both designs have fewer ORs and beds than an LPD-17 study (
link), they are dramatically less expensive (the conversion of 4 LSDs could be done for the cost of a single LPD repeat.
If new build construction is required then I think that an LPD-17 repeat is the least-bad option. While a dedicated hull would be nice being able to tie into an existing logistic train and crew training system would potentially offer lower life cycle costs, something that must be kept in mind in the current austere environment.