I'm trying to use Sparkfun's Differential I2C Breakout circuit into my own design, and I'm looking to replace the RJ-45 connector. It's too big (having a footprint size of 15.24 mm x 15.24 mm), and I have some requirements that I need to meet. The original board uses an Ethernet cable to transmit the differential I2C signals across long distances. I'm trying to do the same with another connector.
Due to the environment that my project will be in, I have to use a shielded, twisted-pair cable, with the length of the slave sensor being 20 meters (max) away from the I2C master. With these constraints, I was thinking about using HDMI, due to it being readily available and meeting all of these requirements. However, based on some footprints I researched, the HDMI footprint is too big. Thus, I'm thinking about using a micro-HDMI to HDMI cable instead. HDMI has more than enough pins for my needs, but I was wondering if there were any other cable alternatives that will fit my needs and has a small PCB footprint?
EDIT: So, after some discussion and thinking, mini/micro HDMI might be okay in the long run for 3 meters, but in the long run, when I need 20 meters, HDMI is a no-go. It won't be enough to transmit power, so I'm going to need a higher gauge wire than AWG-30. I can't think of any pre-assembled cable assemblies that fit the length and other requirements for shielding, so is my only choice to make my own cables for this endeavor?
EDIT: To give more information about my board, it's more or less an I2C multiplexer board. I'm working off of a Raspberry Pi Zero and an Arduino Nano, and the size of the board is 2 inches by 3 inches. This configuration is meant to read from 8 I2C sensors, so I'm trying to fit eight differential I2C circuits onto one board. The Pi Zero and the Arduino have to be mounted on the board (though for the Pi, I'm not including the 40-pin header as it's not needed); therefore, most of the space is being taken up by the mounting holes of the Pi Zero and the Arduino's footprint, if that gives any indication of the amount of space I'm left with. So, with the 8 I2C sensors, imagine having 8 of the Differential I2C Breakout circuits on one board. I'm trying to find a connector that can deliver the two differential signal pairs as well as power/ground just like the RJ-45 used in Sparkfun's board. In terms of maximum size, given the size of the RJ-45, my max dimensions for the connector is approximately 10 mm by 10 mm. This is mainly just to ensure that there is enough space for adequate routing of the 8 differential circuits.