Although operating within the single market rules, Switzerland aren't in the customs union. Swiss customs are famously picky. They even have limits on meat and poultry products. Many Swiss shoppers cross to Germany and cross their fingers they don't get stopped on return. It's rare for private autos to be stopped but not entirely unknown. All lorries have to clear customs no matter what. Waiting to clear Swiss customs controls can be horrendous especially on a Monday morning.
I've heard of Swiss residents who have 'arrangements' with people in border towns on the German and French sides to use their addresses when ordering from Amazon and the like. I see you've now posted your packet, so my next long shot question of 'do you or your friends know anyone on the German or French side who could take delivery' is now moot.
Of course, the current Swiss situation will apply when posting to the whole EU post January 1st. Happy days.