gophert I think we're going a little sideways here.
I've found (but don't have yet, obviously) a load cell that should be fine with 3.3V, a rail to rail IA that starts at 3V, gain I can set with a suitable resistor at what I think should be minimum 50 (3.3 / 0.066V) but may need to be higher when I get to working it out. The specific figures aren't my problem (yet), and I know I need an amplifier.
I'm selecting a load cell that I will use the entire range of, and the power supply is provided by the game controller. I know people have made, and sell, kits for this type of thing (same controller, even) that don't use any external power, just the 3.3V the controller provides, so if I can assume from that it should be fairly well regulated. (if you're curious, the load cell in those kits or examples is not the type or range I want to use, so I can't do a straight copy)
My question at this stage is simply: with that load cell, and that voltage, and an IA like the AD623, can I expect to get clean enough results from something like a protoboard setup (with the IA plus various components to provide the gain and some interference and input protection, as detailed in the datasheet but still to be looked into by me) to give 1024 basically clear steps across an output voltage range of something like 1V, or perhaps 3V (or whatever it happens to be, in that ballpark)? It won't be buried in/next to any other equipment (power cables no closer than 20cm or so, computer at least 30cm away).
I can work out the figures with some research and time, I just don't know if amplifying voltages in the range of 0.3mV to 66mV is going to be reliable enough with a bit of a hack job. The IA datasheet talks a bit about RF interference, and ground return impedance and using PCB ground planes to reduce it, but I don't know how much of that is really more related to 'busier' installations and smaller voltage steps than what I'm considering. All the numbers don't tell you what experience probably does.
Things like temperature drift, detailed in the load cell datasheet, I can safely ignore for my application.