They're made on a griddle (thick frying pan) not the oven. Dries them out fine. I've made them once, they need quite a lot of fat & are very high calorie count. I ate mine while around in the house not walking, and put on weight immediately. They were fine but as you say, a bit of practice helps.
I'll certainly use them if I'm going to do any strenuous pack walking. I'm minded to try it with some cooked smoked dry fish, like mackerel or kipper fillets. I think that will travel well and fits with his historical period context.
