Trail running with a puppy

Hello, wise dog owners. I have a potentially dumb question, but isn’t that what Internet is for?

I’m looking into getting a 5 month old moyen poodle puppy and I am training for a trail race. Starting spring I will be taking 1.5-2h trips drives (one way) for my long runs in a nicer area almost every weekend. So, I understand that 8-9 month old puppy is nowhere near old enough to run 20+km with me. However I also do not want to leave him home alone for so long and miss out on all the excitement.

I was thinking to alternate between the dog walk and jogging with him in the backpack. Is it a bad idea? Has anyone any experience?

I also looked at dog strollers, it would obviously be easier for me to jog with, but they are pricy and I do not always know what kind of terrain I’m walking myself into.

Thanks for advice!