Not sure you get VLAN’s concept! They do extend the IP range by creating another 255 address, but it requires setup on the routing side to allow communications between them. A separate network is what VLAN is all about, but not like you describe it.
Also what is amazing about having more than 255 IP devices, it is not normal I know but I do have a large house, large number of IP devices, and a big family. What is efficient use of space? My DHCP assign IP address efficiently. Am reducing the use of WiFi devices as much as I can, e.g. went Zigbee with LeakSmart instead of WiFi.
Anyways, I was hopping for a tip, I already running now with no issue at all, although not best practice but it works so far, am keeping things under monitoring to see if am missing anything.