On our network, we use 10.a.b.c IPs for gear: a=tower, b=tech, c=device. So 10.12.12.x for instance are all ePMP gear on WJSG radio tower, 10.12.13.x are PMP450-365 same tower, 10.32.12.x is ePMP in Bennettsville, etc. (and we reserve .2 for CMMs, .3-.9 for APs, .10 for temporary admin usage)
So we use a mikrotik RB751 $50ish router. One wired port and wifi are bridged together, handing out 192.168.88.x DHCP. The remaining wired ports are bridged together with 10.12.12.10/24, 10.11.12.10/24, etc all assigned to the network-side (vs admin-side) bridge. Also, 10.1.1.10/24 and 169.254.1.10/24. Then in the firewall I use a Masquerade rule so any traffic from admin-side going to network-side gets NATted behind whatever IP is in the appropriate subnet.
End result is that we plug the POEs on each truck into the network-side ports on the router, connect with tablet/cell/laptop via wifi (or that one ethernet port bridged together with the wifi), and have ready working routes to the connected gear on the other side, including default IPs, with no time or effort spent setting up needed subnets to reach gear.
Sorry, I don't follow the question. I've set up with POE and router on our bucket trucks that they use installing and servicing subscribers. What do you mean by "at the subscriber side"?