One of the advantages of the SNCF Voyageur program (as touched on in this existing question here) is VOTRE CARTE CONTIENT VOTRE BILLET. This means that when booking your ticket online, you can enter your Voyageur membership number for getting points, and opt to have your ticket "loaded" onto your card. You then don't need to collect or print tickets, you just show your Voyageur membership card during a ticket check, which gets scanned much like tickets do. (Show them the QR code on the back, they scan it with their handheld device, it goes green, all good!)
One disadvantage of this is that you don't have a handy ticket with train times on it, and especially not seat numbers. This can make boarding a little tricky.
Obviously you can hunt through your emails to find the booking confirmation, and look up the train + seat details from that. You can also write down the details or print them out, but that's an extra thing to loose, and partly negates the point of the card!
Is there perhaps an app for your phone or tablet from SNCF, where you enter your Voyageur card details, and it tells you about seat+train details for upcoming trips? (Ideally with caching for offline use!). Or can you show your card to someone at the station to recall the details? Or a ticket machine? Or something else for when you're at a station with no internet, knowing your're on a train "about quarter past 8" with no idea of what seat, and only a best guess of if that means the 8:12 or 8:22!