M4300-52G-PoE+ Max Private VLAN or Max Isolated Ports

Hi there, 

I'm wondering if there is a maximum amount of Private VLANs in a M4300-52G-PoE+ switch. 

Does that number change when stacked to a maximum per stack? 

Is there a maximum number of ports that can be in set to isolated or community in an M4300-52G-PoE+? does that number change when stacked to a maximum per stack? The datasheets just seem to say "Yes". 

My goal is to have something similar to 'client isolation' on Wireless Access Point but with wired clients (ideally without 802.1X).

I'm looking to achieve this by having 40 of the 48 ports as host ports in an isolated private VLAN and 1 port with a router as a promiscuous port in a primary private VLAN. That router would offer DHCP but also deny any L3/L4 traffic that tries to go through it. 

Does the above make sense? Am I missing anything obvious to achieve the goal? Are there any limits I might hit? 

Many thanks. 

T