Similarly forced to go through a corporate TA but I've managed to find one good person there who I've built a bit of rapport with and has been able to help me get creative, such as our rule for certain destinations/duration to be in Y or W, the TA will find me an expensive Y/W ticket to bill to the company, and then allow me to change to a cheap J fare, sometimes on another flight or airline, and bill me that fare difference to a personal card.

Not sure how above board this is, so I may regret posting it on a public forum...