Router-On-A-Stick, Loopbacks, and Management

Quick question. I'm using router-on-a-stick to a switch (Router --> Switch --> Hosts), which has 3 VLANs for hosts, plus a management VLAN makes 4. I'm using g0/1.1, g0/1.2, g0/1.3 for hosts and g0/1.99 for the management VLAN, so the hosts below the router and connected to the switch will have a gateway to the management subnet. I also have a loopback address for management purposes (this is the address, for example, that I would SSH into). The rest of my network is also using loopbacks for management and I'm looking to keep things consistent.

Addressing is as follows:

G0/1.1: 172.16.0.1/24

G0/1.2: 172.16.1.1/24

G0/1.3: 172.16.2.1/24

Lo0: 172.16.255.235/32

Management subnet: 172.16.255.0/24

My issue is with adding an IP to G0/1.99. I already have the /32 loopback configured, so when I try to add 172.16.255.1/24 to G0/1.99, it tells me it overlaps with Lo0. If I understand correctly, this is because I'm adding the same subnet onto a router twice, so it denies the change. But I want the Lo0 interface to be in management, and the G0/1.99 to be the gateway for management, so both have to exist on the same router. How can I work around this?