If you haven't noticed your character tends to slide down slopes, just find one that is long enough or even better : make your own.
My advice would be to have a canister so you can deform terrain with the "flat" option (get your Terrain Tool out with
then press
). If you start digging at an angle then switch to the "flatten" option, you'll be able to create your own slope.
Keep digging/flattening until you are satisfied.
The trick is that you can accelerate/brake when gliding with
and
, so brake to slide for a longer period of time but not too much or you'll stop!