Okay... I have a few ideas... may seem crazy but, here goes.
So, my family owns a class A RV. We've taken many, many, many cross country trips with this beast and my dad LOVES driving it. in fact the dork was just talking about how he wants to go out west. So... option A (obviously I haven't talked to my father yet... but he's always down for a good travel!). So, possibly we could drive out to California and pick you guys up and drive back home. Since we live in Wisconsin, MN isn't far at all. Obviously there is the cost of fuel right now, so you'd have to consider that, but I'd guess it'd be a lot cheaper than renting an RV! And since we'd make a vacation out of it, we'd need to know a little in advance so we can leave early and plan some stops on the way out to California!
Or, you guys could take the train part way and we could meet you any where along the route.
Option 2 via Trisha: We can drive our RV down to the Chicago train station and pick you guys up and take you home. I know it's not THAT long of a drive from Chicago to MN, but with a premie it might be.
So, sadly those are all the options I have. I'm really sorry you are in this prediciment... but hopefully it'll all work out.
PM me if any of these ideas are appealing to you. UPDATE - FYI: I have talked with my parents and they are willing to do this! It'd still be expensive though Around $2,500 just for gas!