Hate to say it, but if you want Legacy Airline pay, then go work at a Legacy Airline.

Spirit is a low cost airline, and the pilots are paid accordignly. It is like a guy flying a BE1900 at Ameriflight expecting to make UPS 747 Captain pay. The single pilot BE1900 is probably a little more demanding and works more hours, but the UPS 747 Captain makes 6x the money (or more).

Different jobs, different pay.

Go to a Legacy Airline if you want Legacy Airline pay.