The breadboard fits in sideways pretty well. The earlier version on the robot (ted gave me his) doesn’t have enough space to slide in the breadboard with the rangefinder attached. The updated version has enough space to slide the breadboard in and out with the rangefinder attached which would save the hassle of plugging it in through the window. Also, the rangefinder fits in the “third wheel” window quite nicely as it is. Let me know if you still want to design it with two holes for the rangefinder to look through and I will measure out the dimensions or we could leave it as is.
The battery pack fits in behind the breadboard perfectly in this configuration and it balances out the weight. The downside with having the breadboard rotated is that the window is far less useful with only around half of the board accessible. Kevin mentioned that it would be preferable to mount the battery pack underneath the chassis. In this configuration the battery pack could be easily zip tied to the underside without getting in the way of the breadboard.
See below for a drawing with dimensions of where the holes/slots should go. The drawing is pretty unclear so just to clarify where the holes should go: to position the bottom two holes move 10mm in towards the centre of the bot from the bottom of the biggest slots. The top two holes are 15mm away from the nearest two sides. You could put slots in these positions instead of holes (slots might be better for zip ties) . A good slot size to use would be the same size as the ones used for the “third wheel”