Ratdog is nearly 6 months. Going by what I've read, he should only be walked for 25/30 minutes. However, I've also read that a longer period of exploring is good for puppies.
I was hoping to take him out for a long walk. 15 minutes of road walk then a good explore of some local countryside. Does that sound too much? He's a cross breed and both are high energy. He's also very nearly fully grown if not already.
I think he'd love it, but I'm wary of overdoing it.