First, wild camping isn't illegal, it's a civil matter. That means that it's between the landowner/tenant and you to sort out, with the law being firmly on the landowner/tenant's side.
Second, if the weather is really so bad that you have to stop and retreat to your tent, then surely it's bad enough for the landowner/tenant to be indoors too, except he'll be in more comfort.
Third, if I was a landowner/tenant and the police came knocking on my door to tell me that a fully-laden dead backpacker, equipped with tent, sleeping bag, stove, food, etc, had just been zipped into a body bag and carried off my property, I'd probably be thinking... "Why didn't the silly plonker just pitch his tent and wait until the weather cleared?"