The only 1x1 items for the equipment grid are personal solar panels and belt immunity equipment. Once you start using portable fission/fusion reactors there's no need for solar panels any more, but that leaves a single belt immunity item in a 1x1 space meaning it's impossible to fill the equipment ...

Why does your son need the expansion? That way you only need to spend $45 to get a full, feature-complete game to play with your son. If your son is as impulsive as you say (and as all kids are, no slight against your son), surely he'll be bored of it long before even beating the base game. I think ...