CANbus Handshake?

Currently, using one CANbus module, we are trying to do a handshake to a system control unit. Only way we can see to do this with your design is to run a loop where we:
turn off canbus reception,
turn on transmission,
transmit step one of the handshake,
turn off transmission,
turn on reception,
wait for ack,
if no ack, rerun loop.

We are doing monitoring of the CANbus for diagnostic reasons all the time, so when we turn off the reciever, we lose messages.
Is there a better way to do this? are we stuck with this due to comm protocol? Do we need to run 2 canbus modules, one just for transmitting? and on that note, why dont you guys have 2 transievers on that CAN2b module? there sure is room for it.