Panasonic Toughbook FZ-55, either Mk2 or Mk3. They can be had cheaply on eBay, and you can buy parts directly from Panasonic if you want to.
If you have money to burn, the new FZ-56.
If you have money to burn, the new FZ-56.
You are precisely correct, which is why you should evaluate them. Not only will it run any code you want it to, it's extremely well supported in Linux, built solidly, and you can buy parts directly from Panasonic.
Not all of them are as bulky or heavy as the fully-rugged models. This one is "semi-rugged", not that much thicker than a ThinkPad.