Jun 28, 2017 - 8:05 PM
Early December is autumn and low season, so I would not count on this to be honest. But, if you're lucky there will be sufficient snow and a company who may do this around this time too (probably in weekends). Your best bet is to visit the local tourist office and ask for the nearest option.
Kutscherei Reichenbach organizes horse sleigh rides to the Lauenensee (Lake Lauenen) near Gstaad. Not exactly in Wengen but at least in the Bernese Oberland :-)