I decided to use a time tested approach of trial and error. This is what allowed access to proxy2:
ssh -t -t -D proxy1 -R proxy2:127.0.0.1:proxy2 -p remoteSSH [email protected]
In Firefox, I can now enter:
https://127.0.0.1:proxy2
which will send the connection through the tunnel (proxy1) to the local proxy (proxy2) essentially becoming a local-remote-local tunnel to a specific port.