Awesome idea there Brandon!
Personally, I would be looking at something a lot more narrow and hard compared to gokart, 2 wheel truck, or golf cart wheels/tires. Going to be VERY HARD to push/navigate (impossible to steer) around on squishy/wide/ small diameter tires dude, no matter how cool they look

Mrs Nordic can plug in here any time she wants, but from experience, solid, hard wheels/tires are the way to go here, limited surface patch, etc.
Try and find some good lookin, SOLID wheelbarrow wheels/tires. With your skills, you can make them look trick!!

And, just me, I would mount the seat using some old valvesprings to create a rocking action when using.........you'll thank me later for that one

Ray