Stan Prevost wrote:
If I put the desired altitude in the plan, then the controller knows that I
want 12500 and can tell me to "maintain VFR On Top at or below 12500". If I
don't put it in, then he has to ask me what altitude I want

No he does not.


or just
arbitrarily assigns me something

Say unable. OTP is a VFR altitude and no separation is provided. The
only time a controller should start trying to nail you down is as you
get close to your destination and you will need to be fit into an
arrival stream.