Load balance and 2 lans

Good day. I would like to configure a edge router poe.. with load balancing / fail over..

eth0 and eth1 for the dual ISP

but i need 2 lans.. /23 eth2 for unifi access points.. and and eth3 and eth4 for the workstations.. but i need the both lan subnet can communicate to each other.. can't do vlans due to we current dont have managed switches..

thank you in advance..