Can it be done...yes with a lot of patience and visualisation of the topography.
Where to place the pit, well if it's long enough then this is the obvious location.
I have to say that the concept reminds me of one of my older designs, which I called Extreme.
The original is
Here
and I then did it in Sketchup
Here
The multiple crossovers aren't the main point I was thinking of, but at the centre you have 3 levels crisscrossing
Orange being ground level, with Pink being bridge height, with Blue higher still. Getting that right and to look right would be a total nightmare ... not impossible but very difficult.