On the day in Sopel I ended up doing a walk I didn't intend - or most of it! There's an easier walk but I ended up on the Piène Haute walk and followed it as far as the Italian border when I returned by the way I came. The day before we'd commented that we hadn't done a walking trip in Italy so this walk nearly changed that!
Border posts are a little less active than they were post Schengen:
1943 was when Italy changed sides and supported the Allies. The walk was pleasant and shady with views over the river canyons. It appears that I made the right decision to turn around at the border as another party found the rest of walk was difficult route finding.
Afternoon was spent at the hotel admiring the views of the mountains and Sospel. We had mixed views about the hotel, beautifully situated, food was good but the management was a little off-hand (at least to us!). There were now 4 Inntravel parties all heading to Menton the next day so the evening was spent finding each other and deciding who was going in what order!