If you still REALLY want to do some "serious, long weekend trips" as you stated in your OP, you may want to rethink the strategy of forcing your current bike to fill that role. If you're going to tour, you just cannot beat the comfort and functionality of a Touring model HD.
Now, it appears that financially there's no way you're going to be able to trade for a new one without significant amounts of new cash coming from you.
Several options:
1) Do not trade in your bike - sell it yourself and get several thousand dollars more
2) Consider a well cared for, low mileage USED Touring bike
3) Combine option 1 and option 2 and you might come out closer to even than you think. Of course you lose that special feeling of riding a new bike but there's time for that in your future!