Help with mechanics of boarding TGV from CDG to Avignon TGV

Short answer: no one cares.

Moderate size bags go overhead, hopefully near your seat(s). There are racks usually at the
ends of each car for larger bags; it's first come first served.

If you're seated in a row that is back-to-back with another row, the area underneath the seats
can often accomodate a larger bag.

As long as you can lug it on the train, no one will most likely count the # of bags you have.

If the train originates in CDG (you'll have to confirm this), then you may have a few more
minutes to board and get your bearings.

There is no scan of tickets to board the train. At some point someone will come by and scan
your tickets, so you should have them on your phone or some handy device. You may (someone
can confirm) scan your ticket to enter the boarding area at CDG.

I would, either beforehand or at the CDG station while waiting for the train, try to ascertain which
car you are in and where it will more or less stop along the platform. You want to be fairly close
to the car you have your seats in so you don't have to walk through a lot of cars with your bags.

We traveled on the TGV from CDG to Avignon last April. We were a bit jet lagged but, if I remember correctly, it was pretty straight forward. There was some confusion on which door to go out but I asked a lot of questions of the workers-most spoke English.
Ours was not a Ouigo but we each had a bag besides our personal item (which was the size of a daypack and counted as hand luggage- which we kept with us). The larger bags needed to be stored at either end of our car and were stacked along with others. There was some room above our seats for bags but not for anything of size. When getting ready to get off, there seemed to be a mad rush to grab your bag and be ready to disembark. Hope this helps some.

@shoeflyer: What you are describing applies to trains outside of France, but SNCF is now run by former Air France managers, and they like to introduce the things that people hate about air travel to train travel.

So now, to board a TGV you indeed need to go through a gate, and have your ticket scanned. So better be there about 10 minutes before departure, as there can be queues.
And on OUIGO you have all the things that people hate about low cost airlines: You need to pay extra for selecting a seat, extra for luggage etc... And at one time you even were expected to check in half an hour before departure, but maybe somebody at SNCF realised how ridiculous that was.

amrunner4 - Just a note of caution. Believe some of the info in the responding posts so far is for regular trains, not the OUIGO train you asked about. Hopefully somebody who has recently ridden an OUIGO train from CDG can respond with the exact info you are looking for. Have a great trip!

Yes, this is an OUIGO TGV train from CDG to Avignon. I am concerned that the daypacks will be well beyond what is allowed for "handheld luggage" dimensions (36x27x15cm). So essentially, we will have 5 bags that they would classify as "carry on" (55x35x25cm). I will option purchase an extra bag just to cover this.

Thank you all for your insights. I certainly helps to have an idea of what to expect.

Your Ouigo train ticket includes one item of cabin luggage (55 x 35 x 25 cm) with no weight limit and one item of hand luggage (40 x 30 x 15 cm) so if your have only one daypack and it meets those hand luggage dimensions then bring it on the train as hand luggage.