Knowing the off piste and mixing it up with some of the regular trails is key to alps singletrack in the portes du soliel I have a 30ish mile loop which is a mix of on and off piste singletrack, double track two quiet dh runs but doable on 140mm bike.
Oddly over is Switzerland I overtook three dhillers as they were not running wet screams and had stalled on the gnarr muddy descent 😆
Having been here 6 times now and we have a guide for a couple days we have some pretty nice routes.
That said the advice above is sound I can imagine it would be easy to end up fully DH orientated and thrash the runs in Lets Get, the Pleny and Chatel there is more here than that, but do a search as this is asked alot this time of year, we only used an all in company our first year and since then solo with a guide for a couple of days as we see fit.
Have fun and be safe never seen so many air ambulances and riders in slings than this year….. The slippy condition last week didn’t help, and it hammered with rain last night so suspect a busy day in Thonon