I think the key to your trip is “Support/sponsorship“, or a You Tube live Stream.My tuppence worth, advice on long distance walking North of Scotland.
There's now an John O'Groats trail
But at the Southern end it does skip a bit of coast such as the Black Isle and then the Portmahomack peninsula.Comprehensive free route guide to the John o' Groats Trail - a new route under development from Inverness to John o' Groats. Includes free OS maps and descriptions of each stage.www.walkhighlands.co.uk
There's no trail across the North Coast and a lot of it is cliff and bog so you end up walking on the road, much of which is single track and shared with the NC500.
From Cape Wrath to Fort William there's this.
The Cape Wrath Trail is an unofficial, unmarked and magnificently wild long distance route from Fort William to Cape Wrath in Scotland. Walkhighlands features a comprehensive guide to the route.www.walkhighlands.co.uk
Occasionally we get round the coast folk popping up on Facebook and local media. As they travel they are offered beds and meals, this is more successful on east as more populated.
The issue with food is that, if on foot, the distance between shops on the West and the North.
But with sufficient social media presence and doing it for the right charity, locals can be very generous in terms of transport and accommodation.
Or a really active Tinder account