Personally I think some of the tactics proposed cross the line and constitute fraud. When you submit your ticket after your flights to receive something of value you already know you are not entitled to, I'm not sure how you could think that is a "gray area" ...

I flew Priceline tickets a few times and when I received Delta tickets I would get my SkyMiles number put on the tickets so my status would be in the system for preferred seating and priority stand-by (when it was allowed), but I would have never even considered submitting my ticket stubs after the fact to receive mileage credit.