Load Balancing a pool member listening to different ports

You should be able to define the pool with three members, all using the same node IP address but different ports. (The monitor is not necessary. I added it during my testing.) For example:

ltm pool mixed_port_pool {
    members {
        10.1.20.18:2375 {
            address 10.1.20.18
            session monitor-enabled
            state up
        }
        10.1.20.18:2376 {
            address 10.1.20.18
            session monitor-enabled
            state up
        }
        10.1.20.18:2377 {
            address 10.1.20.18
            session monitor-enabled
            state up
        }
    }
    monitor http 
}

You will almost certainly be limited on the load balancing method you can use with such a pool though. Round robin will certainly work and is what I tested with. But I'm suspicious of anything node-based or dynamic since there is only 1 node involved.