I too work it every day and I do it with sales. Nobody wants after 7pm and many refuse any weekend spots. The only thing after 7pm and weekends are good for is bonusing units to get cost per thousand low enough to hopefully win the buy. At one station they'd sell an add on of say 10% of unsold avails after 7pm or on weekends for a set dollar amount, typically about 10% to 15% of the daytime weekday spot rate.
Finding somebody that can sell and is an on-air jock is about like buying the winning lottery ticket. Here there is virtually no cross-over from sales and programming. Simply put, if they can sell, they aren't going to pull an air shift.
Adding a 7 to Midnight shift likely will be a cost not a profit center and the only chance at anything is via local sales. Even then the universe of possible advertisers is minimal. Worse yet, the spot rate is so low the salesperson would rather manage their time selling daytime where the same amount of work makes them more money.
To say we lack vision is not dealing in reality.