A few other things to consider. Check the balance of the wheels by spinning them and checking for overly heavy spots where the wheel always will stop in the same spot. Almost all wheels will be a little unbalanced and no big deal but a really heavy spot could make a difference and if so try rotating the tire on the rim or moving a wheel magnet, if you use one, to a different spot on the wheel to see if you can lessen the effect. If you like your riding position on the bike I absolutely don't recommend changing it by moving seat, bars, etc. around as the other 99%? of your ride time will affected. As mentioned check if your headset is tightened properly. Your tire pressures are probably fine but just for experimentation purposes try adding more pressure to the front and see if the wobble goes away or improves. Even though this is a Trek CF frame which very rarely are not perfectly straight you may have got a bad one so check for alignment. Also I have never heard of complaints of speed wobble with these so you may just have a situation of a perfect storm of small niggles combined that happen to create this situation and removing just one of them may solve the problem. I know you said you're not interested in moving your body around too much to stop this but just pressing your knees together against the top tube often will stop a wobble.