Maybe the folks who maintain the route will have a better answer, but my impression is that the length of the TA has nothing to do with "avoiding obstacles like particularly unsupported areas or difficult passes". It seems if anything to avoid large towns and keep you in the boonies most of the time. It also seemed at times to intentionally do more climbing than absolutely necessary. That said, I found it to be a great route.
Seven weeks is tight but still doable and you could cut mileage in a number of places along the way.
I really liked the TA, but if you want a shorter more direct route you can always:
- Plan your own route.
- Do the Southern Tier.
- Follow one of the fast crossing routes used by races (like RAAM) or tour companies who specialize in fast crossings
Personally I think you are missing out if you focus on too much on "the ultimate goal of crossing the country" at the expense of seeing the sights and meeting the people, but different strokes.
Another option might be to do half of the TA this year and half next.