Are you sure what kind of problem you have, a radiated failure is caused by RF emissions near your kit, if its a spike on the power or signal lines then its a conducted problem.

Radiated problems need good mechcanical design as well as suitably filtering all ingoing and outgoing connections. PCB layout and the design of the enclosure also have a significant effect.

Conducted problems howerer will only need suitable filtering etc on the problem line, although this may have a knock on effect on RF immunity/emissions.

If the kit is to be installed in a electrically noisy enviroment then I would add a hardware watchdog, and allow for supply dropouts/brownouts as well.