Take a look at crazyguyonabike.com - there are some journals from folks who have traveled with dogs (though I don't think any are quite that large). It's also a great place to get information about different touring bikes, and what works for different people.
I have 2 touring bikes - a Bike Friday Crusoe and a Trek 520. ISTR that my 520 was not much over $1000, and I bought it at the end of the year. I've not done loaded touring on either (though it is in the plan for the future). I love both bikes. What kind of bikes do you have now? Is there a possibility one would do for short tours to try it out? Since you're touring with your DH, one of you could be lightly loaded and pull the pup in a trailer, and the other could carry most of the load. There really isn't that much more gear for 2 people than 1. You could pull gear in a trailer or use panniers. It's a matter of preference.
Good luck, and let us know how your decision process goes - as you said, we're great enablers
ETA - Make sure you think about how to get you, your pup and your gear to AK - 50lbs would have to fly cargo, which would worry me...
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