Traveling Mini in an RV as a router?

[rvmini]

I am trying to figure out how to best set up my network in an RV and I am looking to you folks for suggestions.

Here is the equipment I have but I am unsure if I will need to use all of it.

Core 2 Duo Mac Mini
Airport Gigabit Extreme
Airport Express
Apple TV
Sprint USB modem
Printer
2 MacBooks

I have a Sprint USB modem that will be my internet connection. Since I cannot hook this up to my AEBS "because it requires a driver" it will have to hang on the Mini.

I know I can set the Mini to share its internet connection, but how does that effect the rest of the network. I need for the MacBooks and Apple TV to get IP address.

Do I need the Airport Extreme to handle DHCP? Would I be able to hook it up to the Mini's ethernet port to get the internet information from the Sprint Modem? Have it be the DHCP router Or do I need it at all. Is there another software router application that can do this wirelesslyf from the Mini?

I need to get to the printer from the laptops and the Mini. I can...

A) Hook it up to the Mini and share the printer.
B) Put it on the Airport Express to access it wirelessly. Which may be better since I will not be limited to its location.

My Mini will be in the back of the RV with the monitor.
The Apple TV will be in the front lounge connected to the TV.
The printer will be where ever I can find a spot for it.

Can anybody please point me in the right direction. It would be much easier if I could put the Sprint modem on the AEBS. My other option would be to spend $1600 on a mobile internet solution box with a router for RV's, But would rather not spend that kind of money if I don't have to. I would like to use what I have if it is possible.

Thanks