Question on irules for multiple nodes.

Sounds like you want to mirror the traffic to all pool members instead of spreading traffic across them. In this case you would create a clone-pool for each member then attach this to the virtual server. The first pool member would be in the pool attached to the virtual server. The rest of the pool members would be in clone pools. In other words each pool will have a single pool member.

If you have the following pools with a single member in each...

pool1 - 10.10.10.1:80
pool2 - 10.10.10.2:80
pool3 - 10.10.10.3:80
pool4 - 10.10.10.4:80
pool5 - 10.10.10.5:80

The then following commands will create a mirror of traffic to the members.

tmsh create /ltm pool pool1 members add { 10.10.10.1:80 }
tmsh create /ltm pool pool2 members add { 10.10.10.2:80 }
tmsh create /ltm pool pool3 members add { 10.10.10.3:80 }
tmsh create /ltm pool pool4 members add { 10.10.10.4:80 }
tmsh create /ltm pool pool5 members add { 10.10.10.5:80 }
tmsh create /ltm virtual myvirt destination 192.168.10.10:80 profiles add { tcp } pool pool1
tmsh modify /ltm virtual myvirt clone-pools add { pool2 pool3 pool4 pool5 }