$1500 doesn't cover what?
So this is 18k a year, guaranteed.
If two guys offered you this you'd just say "naw I'm good" and keep it moving leaving 36k on the table to work no more than 20 days a month per month?
Both agree not to abuse privileges nor use you for more than 10 times a month.
A third guy makes it 54k but you can only work up to 30 days a month. All three can be conservative and see you just 5 times each. You can book your other independent dates around your retainer (SD's) clients.
That's not good enough for you? You'd tell the guy to walk the other way offering you 1,500 a month.
Ok. Gotcha.