That sounds like usual hotel scenario for AP+Phone for each room with extra step... Are you sure that those "48 routers" are necessary? Are they gonna work only as PoE splitters and switches or will it really have some routing task?
fiy - for example CAP ac
can do poe-out (passive only!) so if your phone accepts passive POE (very unusual), you wouldn't need router. If your phones require 802.3af/at (very common), then I am afraid there is no option available anyway - as far as I know, there is only one model (RB960PGs) with 802.3af/at poe-out except large switches...
(@mkx already said same point)
I am aware my next words will be controversial but fact is that there are ongoing issues between some AP and some wifi devices. If my assumption with hotel or other public venue is correct, then I would not recommend to implement solution which has known limitations and compatibility issues. Mikrotik is great in terms of flexibility and routing, but their PoE and Wifi is not really the best nowadays.
My last sentence can sound like I am trying to harm Mikrotik, but truth is exact oposite - we all know these issues are real and if someone order 48 AP and then they start getting complains due to disconnections or speed issues, bad reputation will harm Mikrotik way way more.