Is it possible to combine two Mario Kart Live packs to create longer courses?
With a Mario Kart Live pack you get four arches and two curve signs.
To play the game multiplayer, each player needs their own Switch console and physical Mario Kart.
When playing with two players, can you use up to eight arches and four curve signs in your course?
According to Nintendo, only 4 gates total but up to 8 arrows (more can be printed). A gate can be passed multiple times along the way.
https://en-americas-support.nintendo.com/app/answers/detail/a_id/53131/~/how-to-create-a-course-in-mario-kart-live%3A-home-circuit