The area you visited gets quite a bit of pressure, but your in the right country, and I guarantee there are animals there. In fact any side creeks in the Lewis are worth climbing into for a look. Time spent behind your binos is what will produce animals.
Focus on guts/gullies coming out of the beech forest. Next time leave earlier, climb to the tops in the dark if possible. You need to be glassing prime country at daybreak or not long after.
In areas where chopper activity isn't huge deer will bed down in the tops so it is possible to hunt throughout the day. Also Chamois, while most active during the mornings/evenings, will still be hopping about the rocks during the day time also.
Next time try and get away from marked trails leading to the tops....people activity will keep animal activity to a minimum. Instead, find a nice leading ridge on a map and follow that up, its likely it will have a deer trail on it leading you to the top anyway.
Sidle through the faces above the bush line glassing as you go, find a nice gully edge on dark, sit back and wait quietly out of immediate view. If nothing shows, camp there for the night and continue in the morning. Saves travelling to and from camp.
Using a GPS, map/compass, getting lost up there is unlikely, unless you're a complete air head. With the main rivers and a road splitting the pass finding your way out is easy enough.
Also, remember that wind shifts downhill in the morning until the sun rises then it shifts uphill. Climbing into valleys from below around mid morning will scent all the country ahead of you, so get up and high early and you'll be sweet.
Too bad about the range finder, I hate losing stuff.
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