That's the way to do it. The other way would be to just send the .wav files from the project forlder. But then events will not all line up from beginning of track creating a nightmare for lining up in protools. I suppose you could bounce each track so that they are all the same length and deliver those wav files. How many tracks are you talking about? Export mixdown of each 40 tracks would only take a little over an hour.
There is software you can purchase to convert the project files. Not cheap tho
PC Win7-64-24G i7-4790k/Cubase 9 Pro 64-bit/2-Steinberg UR824's/ADAM A7x/Event TR8/SS Trigger Plat Deluxe/Melodyne 4 Studio/Other things that don't mean anything if a client shows up not knowing what it wants.