Several years ago we went to KC for USSSA 16a and then took a hard right and went up to Sioux Falls, it was a very tough trip, but we ended up playing our best ball ever as a team in Sioux Falls, I have always wondered if we would have played better or been rusty if we hadn't played in KC, this was also the year of the now defunct triple elimination ASA nationals so you were in the fire from your first game out, NO pool play of any type.
In answer to the question, because of the ASA starting and expecting coaches on Sunday at the sites, my best guess would be to find the toughest tournament two weeks before and get on e-teamz and other sites and find teams to schedule on your way up and when you get to Sioux Falls on Saturday or even Friday, in the meantime, get your workouts in and prepare every aspect of your small game in live action if possible. You will need it, both defensively and offensively.
Illinois is almost halfway, no shortage of great teams there, also WI and MN have some really top teams that will give you great prep.
Good Luck and have fun in Sioux Falls, "it's a rocking town!" If you like corn fields, that's the good news, very few distractions for 16's.