You should have no problem booking the reservation the day you arrive. Don’t worry.

I’d probably wait until you got to Europe for travel in March unless it was a Friday or Sunday night. I think you can book “just a reservation” on line from bahn.de if the route starts or ends in Germany. Go to http://reiseauskunft…? Fill in your cities and date/approximate time. Click on the CNL train (click on any special offer that’s available for your train) like you’re buying a ticket and fill in age. You may then have to click on the specific train again. At the bottom next to the red continue button is the option to “book only extra charge.” Click that and then the “pass offer” choice. You should be able to buy just the reservation that way. You should also be able to buy this from one of the on-line travel agencies that sell railpasses, but inflated pricing, shipping fees and handling charges will at least double the cost plus you’ll miss out on any special offers, so you’d end up spending about 55 euros for a reservation you may be able to buy from bahn.de or at the station for 17,50.

With the great specials available for advance purchase on overnight trains, it may be cheaper to buy the ticket with reservation than to burn a day of the railpass plus pay for a reservation. Ticket and reservation in a reclining seat is 54 Euros. Reservation only is 17,50 euros (on the same special offer, regular price is 27,50 euros) plus a day of your railpass is probably worth 35 euros.

I would pay the 10 extra euros for a couchette — and if you’re big I’d seriously consider another 10 for the 4 berth (as opposed to 6) cabin. However, if you’re one of those folks who can sleep in airline or train seats, (I pretty much can’t) you may be fine in a reclining seat. I think my 6’1” husband who can sleep about anywhere would prefer the reclining seat to being crammed into a 6 berth. My 6’2” son couldn’t sleep in either a reclining seat or a 6 berth but could at least live with a 4 berth. Rick Steeves, who looks like he’s about 6’4” on TV seems to be comfortable in the 6 berth.

P.S. Basel Bad station is at least partially in Germany and is operated by DeutcheBahn, the German national rail company. Basel SSB is the station operated by the Swiss national rail company. CNL 40478 originates at Basel SSB at 22:12 and stops at Basel Bad at 22:20. Where to board is kind of a toss-up. All things being equal, I would board at SSB as the train starts there. You can board early and comfortably find your berth and get settled before the train leaves. The stop at Bad may only be for 1 minute?, which can be kind of a rushed hassle if you haven’t figured out where your car will stop, have a bunch of gear, etc. Hauling even a small amount of gear through the cars of a moving overnight train isn’t a lot of fun. However, your German rail pass might not cover the trek across Basel, so you might have to pay a couple of Euros for an extra ticket if you leave from SSB? I don’t know how you’d find out the length of the stop at Bad or whether your German rail pass covers the 3 km between thhe two without asking at one of the Basel stations.