I am planning a clockwise loop of Scotland for 3 and half weeks starting mid-July. I'll cross from Belfast to Stranraer/Cairnryan and aiming for a loop of approximately 1200 km (trying to hook up with the 73 and 78 cycle routes up to Oban via north arran; then considering oban to skye and a loop of skye coastal roads, then across to loch ness and up to Inverness; then returning down through the Cairngorms, QE Forest Park and a stopover in Glasgow and back to the ferry at Cairnryan (by 8th/9th August). The route isn't set in stone either - happy to adapt it and also do some more remote. Another option is spend more time in the north and catch the train back from Inverness to Glasgow near the end.
If anyone is interested in joining on particular legs - please get in touch. I plan to primarily wild camp (with occasional hostels/warmshowers/etc) and generally average about 80 km per day.
All the best
Scotland - mid-July (3-4 weeks) to 8th aug