Seems damn reasonable to me if the damned fool left his shield on as well.
Well, to be fair, you said just suffer the armor check penalties to all rolls. You didn't really specify that it was only for the armor actually worn. Or, to put that more clearly, your wording didn't specifically say that it was only the check penalty for the armor you were wearing, rather than just your total armor check penalty whenever you wear heavy armor while sleeping.
Even if it's only a -2 to all rolls though, that's still a pretty hefty penalty. That's equivalent to being rattled at all times, or always attacking an enemy while marked. Where's the tradeoff for lighter armor? Or for Scale, which doesn't even have a check penalty?
The problem is that you're rather unfairly punishing a certain subset of PC's. It gets even worse because even if you say "no armor at all", the light armor users with high DEX/INT will still have a massive advantage over the low DEX/INT classes that were wearing heavy armor. It's just rather nonsensical and can end up
forcing PC's to always make certain decisions such as always sleeping in a town during an extended rest, using summoned armor for the heavy armor users (thus eliminating 99% of their potential armor enchantment choices) and could even result in unintended and random TPK's during relatively weak encounters because the heavy armor users will practically be auto-hit on anything but a 1 past a certain level.
I know that, but that would limit them to just the summoned property. That would kind of defeat the purpose.
That's something that I worry about happening, is all of the heavy armor uses essentially being forced into taking summoned armor. Your original post about paying extra to add the property to a suit of armor was a decent one, but it still ends up unfairly penalizing the heavy armor users, but mostly just at low levels when money is tight.
The only problem with it is that, in the end, almost everyone is going to add the summoned property to their armor. So why not just let them sleep in the armor in the first place? Otherwise, you're basically just instituting a mandatory tax that they have to pay, but not really changing anything else about the game. What does it actually
add to the game here?