Likely The Container Store will have someone that will suffice. If not, just a simple nylon garment bag should also work.
Unless we are taking just a simple weekend trip with very casual clothing, our typical packing method is to take hanging shirts, trousers, skirt, dress, etc.,
put those (on the hangers) into a light nylon garment bag, zip it up, then fold it into threes, then set it into the RS rollaboard (disclaimer we have the older style RS carry-on that is no longer sold on this site....we would not be able to do this as easily with the new size RS rollaboard). Then once we arrive our hotel, we simply take the garment bag out of the rollaboard and hang it. If we are just staying a night or two, I don't even remove the hangers from the garment bag, I just unzip it and pull out what I need, etc.
We've lugged a tux this way a few times, as well as a sports coat. All came out just fine. If you are traveling in business class (or even comfort class), you could always ask the flight attendant if there is somewhere the inner garment bag could be hung during the long overseas flight. Even if I were in plain ole coach, I would probably very nicely explain my concern to the flight attendant, and you might luck up and have the inner garment bag hung during the long flight (or you could take it out and fold it in three in the overhead yourself, then switch positions (changing the fold areas half-way during the flight. But, seriously, unless it is a linen suit, you should come out just fine with the three-fold method, being careful to make sure the jacket sleeves are not bunched up as you fold.
You didn't ask about packing a tie, but what I do for that (when my spouse will need one), I fold place white tissue paper around it, fold it in half, then carefully roll it (with tissue paper sort of cushioning the roll), then set it into a Tupperware-like container (round), with a lid on the top...then that finds it way comfortably into a small open space in the suitcase. That method avoids a crummy wrinkle that can develop if the tie is folded over trousers and shifts in position en transit.
My husband wears a lot of the Brooks Brothers long-sleeve no-iron all-cotton shirts when we travel (provides some sun protection), and people are always asking me if I iron my husband's shirts each day. NO!!!! Never!! Just packed with the method referenced above.
The challenge when one needs more formal attire is those darn extra dress shoes -- they take up a lot of space, but stuff socks, undies (in baggies), etc. in them.