can we upload our own maps using google sketchup files, or at least have form of creating our own maps.

I would LOVE to have this feature however I fear it may be unlikely... FPV Freerider is built in the Unity game engine, and unless the author built out a system to import maps, all maps need to be present at the time the game is compiled for distribution.

That said, I can think of a few ways you could create a basic 'Map Editor' by passing a grid of characters each symbolizing a different asset or element on the map. Importing Sketchup files sounds scary. There are a few guides on how to move individual models from Sketchup over to Unity, however importing an entire map of 'geometry' sounds like a big task. If you wanted to import individual assets, maybe you could have a special character designated for 'external imports' which would reference a full path to said object to import.

I'll keep thinking about ways the community could contribute to the maps featured in FPV Freerider because that is my #1 desire after playing both titles. The existing maps are amazing, but I love the idea of building my own.

Yes GFargo is correct - there is no easy way to load custom maps since they need to be compiled into the build itself.

And yes, it would be possible to include a basic map editor, but that wouldn't allow the kind of creative freedom I would like.

I hope a solution for loading custom maps will come up in the future, as I also think it would be one of the greatest features to have.