Out of nothing other than boredom over lunch I started looking at this again - 200 miles total distance, broken down as follows:
DAY 1
If we equate that to approx 50 miles per day our first stop could be at Balquhidder (mile 55) where there is a hostel here:
http://www.visitscotland.com/info/accommodation/loch-voil-hostel-p877121#location
OR a Hotel here:
http://mhor.net/mhor84-motel/
Or Lochearnhead (Mile 60) where there is a hostel here:
http://www.stravaiging.com/travel/accommodation/property/braveheart-backpackers
The advantage is that East Coasters can use an alternative route via Fife, Crieff and Loch Earn to get here.
DAY 2
Next stop Pitlochry (mile 105) here:
https://www.syha.org.uk/where-to-stay/highlands/pitlochry.aspx
DAY 3
Next stop either Kingussie (mile 150) here:
http://www.kingussie.co.uk/stay/bunkhouse
or push onto Aviemore (mile 165) here:
https://www.syha.org.uk/where-to-stay/highlands/aviemore.aspx
DAY 4
Then last leg to Inverness for either the train home or
overnight accommodation
If we were being more adventurous (and depending who was interested) we could target 100k per day - looking at the route profile I wouldn't want to attempt any more than that though on a tourer. So 3-4 day trip, hostel accommodation is around £20-25 per night (NOTE: hostel accomm links only there as an example and convenience, if hostels exist generally other accomm will be available) and train back from Inverness to Edin/Glasgow would be around £40 (unless you wanted to cycle back!).
For me it would probably have to be either May or August next year, though don't let that put you off!
Thoughts???