Well, we have the bulkheads made from thick HDPE which also act as frame supports, but the armour is certainly no more than 6mm steel. Thor managed to bend it in parts where it wasnt supported by the bulkheads, and eventually a combination of a hit on our link and bending the steel into the wheel disabled us, but it was all superficial damage and fixable simply with a big hammer, so yeah, I reakon 10mm steel would hold up fine, at least til the spinners come out to play.