Yep - like any other mammal, they can get heat stroke. The biggest risk with Dobermans (and other deep chested breeds) is bloat - and an overheated dogs is more at risk for it, especially if they've been exercising and drinking water.
Ilsa doesn't mind the coat - she's the type of dog that you could put a satellite dish on her butt and she'd ignore it. She's very tolerant!
The pack usually holds a few bottles of water, a collapsible dog bowl, a first aid kit, bug spray, two slip leads, dog booties, and dog biscuits. Sometimes more stuff, sometimes less - all depends on the trip.