Here is an example. I'll use round numbers for the sake of argument.
40k expenses (facilities, equipment, IT, operations)
$150k per year
What's the difference in your example between profit and salary?
I don't see any problem with letting the client know the rate. Makes it much easier to bill for additional items (extra X not covered in the proposal will take Y hours= $Z).
Profit is pure profit or margin. Salary is what you need to live. As an industry expert Richard, you certainly command a higher profit margin than someone just starting. You could work it into salary of course.
Anything not in scope of the original proposal is a separate track of work that would get its own estimate.
Everyone likes to work differently. Not saying the way I do it is THE right way, just sharing how I do it. This is just how I learned to do it at the firms I worked. I don't disclose the hourly because I don't like to sell hours (IE justify why something takes a certain period of time) I feel better selling the solution (IE this solution is worth X), and I like trying to beat my estimate. Just how I was "raised" if you will. Sometimes I go over, sometimes I stay under.