My experience travelling by and through Switzerland 20 + years ago was that no issues in a van empty even on weekends but severe control's when loaded with goods even when transitting through with correct T forms.
On one occasion though I was bringing back a rebuilt London taxi engine for a friend in Italy. Swiss customs required an onerous deposit to guarantee I transitted through the country with goods. Not only did I not have the cash available but strongly suspected there would be issues getting the refund. I left the engine with them and Italian friend and I had to travel back the following day to collect after demonstrating engine was for a privately owned vehicle.
