Board Design and Consultation

Please see the attached file. I would like to build an Android embedded system for IoT. But not for hobby. Industrial. The concept is incomplete. But, gives a simple diagram by which you can get an idea.

All GPIO will need to be Opto Isolated and allow for 24vdc input and 24vdc output. LED indication of the GPIO status. Max 500Ma per output at real world side.

Board needs to be as compact as possible.

Open to ideas. I need someone who thinks outside the box and will make corrections as needed but maintain the overall concept.

I am based in Houston, Texas. I am ready for the most part to issue a job but need some of your thoughts about how this can be done. Your thoughts and concepts will help us to make a decision on who will receive the job.