Well then, why not have a final, fully operational prototype built, then install it and test it to make sure that it exactly fits the bill for what you are intending to make. Then, pull the trigger on the kickstarter knowing that what you have designed does indeed work properly. eliminate all other possible failure points. Then the only risk is that you get 2 machines and both of them fail and cannot be repaired, which would be the worst-case scenario, and extremely unlikely. Like getting struck with lightning unlikely.