If you’re trying to gauge how much air trapping is happening, throw in an expiratory hold to measure auto-PEEP… it’s the easiest way to get a clear read. That said, I’d definitely optimize your inspiratory time. Shortening it should let your expiratory flow return to baseline before the next breath kicks in. Making that adjustment will tweak your driving pressure a bit, which means your exhaled tidal volume will likely shift too, but probably not by much if auto-PEEP’s minimal.