Button box design

I’m in the beginning stages of designing a button box for Euro Truck Simulator. The box will have approximately 54 inputs which includes 3 rotary encoders, lots of momentary buttons and switches, 1 x pull out button for the park brake (momentary) and one pull out button for the trailer brake (pulled out stays activated) and 1 press and latch button for fuel fill.
I’m thinking I would need a Mega to do what I want but I’m new to Arduino and trying to find details is a bit confusing as there is not an anything as big as I want. I think a Matrix is the only way to go but I’m getting mixed messages about how to connect the encoders into the matrix. Any help or pointers would be appreciated.
I’m not looking at switching LEDs on or anything like. Just back-lit buttons and maybe an LED strip in the background to turn on when the Arduino is powered on for visibility.