Best Quality/Value Expandable?

Agree that weight is going to be your problem. Michigan isn't exactly like trying to climb the Rockies, so if you stay in the flat lands, it'll help. And you're going to have to pack light.....really light. Without looking at a dozen models, I'd guess that you're going to be looking at maybe a 17'absolute max with no slide. You don't mention the genders of the children, but it would sure be helpful if you had 2 instead of 1 and 1. Making up a sofa or dinette every night gets old in a big hurry. Also with something in the 17' or less range, you'll likely be looking at a dinette only and no sofa. With your max being 4250#, for safety you need about 1000# of excess, which I don't think you'll find. And you'll need a WDH with sway. More weight. Suggest you start looking at the smallest you can find, which IIRC might be the KZ Sportsmen Classic at 13'. It's available with a rear bunkend and you would have to make up the dinette but it's a nice u-shape. Surprisingly roomy inside with a lot of countertop space, Have you considered a tear-drop style or something like a Casita?? Something like that might work. You mentioned time being a factor and, unfortunately, to find what will SAFELY work with your tow vehicle, you're going to need plenty of online time and then actually going to see it in person. And please, please do not listen to a salesman tell you that you can tow 4250# fully loaded and ready to camp, because it just isn't so. Remember that his/her job is to get your signature on the dotted line and the problems you'll encounter will be all yours. For starters, check the KZ lines, Forest River, Jayco, and you might go on Hybrid Explorer to see if you can get some other suggestions. Good luck...it's going to be a challenge.