Is there some way I can send a file to install directly on iPhone or Android just for testing avoiding sending my .gameproj file?
You can download the GameSalad app for iPhone and Android. You can then install your game in the app over wifi.
Thanks a lot, RabidParrot.
I also asked the GameSalad team. I'm publishing their answer to help people in same situation. This is it.
For this you would need to publish your game and create an apk or app version of the game. For an apk to test on Android, it will be very easy to sign and send them the apk to install on their device. iOS devices are trickier, as they would need to deal with Xcode and have to have their devices be approved under your profile you used to sign the app.
The easiest way would be for you publish your game to Google Play and iTunes, then send them the link to the game where they would be able to download it without any extra effort on their part.
I hope this helps!