Greetings,
I am interested in your project. I can get the job done, at a reasonable cost and time.
I did another project that is closely related to yours, and my client was happy with my work. it also needed a proxy that is undetectable. here is a link to the project:
https://www.freelancer.com/projects/android/Proxy-Using-Android-Smartphones/?ngsw-bypass=&w=f
https://www.freelancer.com/projects/android/Proxy-Using-Android-Smartphones/reviews
I can do this on ubuntu. I can get started even before you decide to award me the project or not. you can award me the project only after i prove to you that i can do exactly what you need.
Anyway, I know the challenges you are going to face with what you require, especially if your modems are same model,and i can offer some advice since i have encountered this issue before. Just start a chat with me, and we can discuss further.
Looking forward to hearing from you.