Hmm…i’ve been from WA to GA and back to WA and never had a problem with drivers licenses. I simply went and paid the fee, took an eye exam and then was issued a new license. I thought this was the case between all states? I would not want to try and transfer a MSF certificate between states as it really is nothing more than a piece of paper printed by your local school. I’ve also retagged my car in each state and that was straightforward. Pain in the ass but straightforward.
I would love to take a cross country bike trip but I don’t think it is something you should be planning on from day one. Seems like too much too soon to me. You could do it but I doubt you would enjoy it. One way out of this would be to buy the used Ninja 250. As you say they hold their value so it may not depreciate at all over the course of a few months. Sell it before you leave and you may not be out much at all and have had several months worth of riding.