If you live in a major metropolis, chances are that www.craigslist.com
is available to sell your tahoe. Craigslist is a free community forum where you can buy and sell stuff for free as well as do lots of other stuff as well. Even if you don't live in a major city that has craigslist, find the one closest to you and I guarantee you can list it and someone interested will buy it.
I just looked on yahoo where Oak Harbor is, and your pretty close to Seattle, and www.craigslist.com
has a site in Seattle, Wa. Give it a whirl , and post your ad, also if you have pics you can post on the ad it'll be looked at more, and remember that it's free to post, you just have to repost every 7 days, to keep the ad up.
I've had enormous success with craigslist, and it's a better bet than the newspapers, etc.
You can ebay it , but sometimes that takes to long.
I would shorten your explanation of why you need to sell it in the Craigslist ad and state that you are very motivated to sell it as your being transfered to Japan for the Navy.
I also would have a certified ( Notary ) bill of sale drawn up as well as any documentation that you can get from USAA , that reflects what your doing and why. I also would get something reflecting your official orders from the Navy showing that in fact you ARE being Transferred, it certainly can't hurt. You may not get exactly what you want for the Tahoe , but it'll sell faster this way.
Gokouun O Inorimasu in Japan !!!