The back to back ticketing shouldn't be 'illegal' or forbidden by the airlines. IMHO you are not cheating but being smart and knowing how to comply with the rules... Same thoughts about the mini-roundtrip within the roundtrip - you are not cheating!

A couple of years ago I was forced to do a back-to-back because I screwed up my flight dates, not intentional. But it was totally worth it, as I ended up paying $100.50 for a roundtrip FLL-JFK-FLL. It was a DL deal through Pensacola, when they launch their CRJ flight FLL-PNS that didn't last too long... I think is back on schedule now.

Different story with the 'throw away' ticket... that, I don't agree with