Yes, indeed the joy of freedom and flexibility. Great to see the pictures of Asynt hills.
There is quite a bit more within the perimeter of NC 500 well worth exploring. Get the OS maps out and seek those hills and lochs which are not on the 'rat run'.
Wild Atlantic Way in Ireland offers some of the easiest wild open camping in the UK. Great recommendations here and justly so. Boundless freedom to stop and camp on sea shores, sea vistas, bog roads and into the hills. Seasonal restrictions on car parks with a 2m height gives controlled access for Cali's, preventing our Great White cousins joining us. Have your Porta Potty ready as public toilets are few and far between in Eire, unlike Scotland.
There are sneaky alternatives in Scotland; Borders, Dumfries & Galloway also explore the peninsulas of Argyle & Bute. Lots of SUP opportunities and some quiet hills. Great country to explore and substantially nearer to you. The Cali absolutely nails Shetland, Orkney, Inner and Outer Hebrides. However, Calmac ferries are in meltdown. Not so for Orkney & Shetland routes. If you look for public shower opportunities in Scotland they are everywhere. And, don't forget that most sea located marinas wil let you shower for a small fee if you ask nicely. (There is an annual Scottish Marina Handbook available giving full details of facilities in each, free and found available in all listed locations)
The Lake District National Park offers some of the safest and easiest access for SUP activity in the country. Current Park and Local Authority controls and restrictions make wild open camping almost impossible. You will end up on the fringes or in a campsite. Your Cali becomes a day van. The hot spots are visited by rangers who will move you on and private land will often block your access. NT car parks offer overnight for £10 overnight. Supporting local farmers on their pop up sites is great for the local economy. Currentlynthis weather is attracting huge crowds. The Lorton to Buttermere Road has been blocked with indiscriminate parking almost every weekend since Easter. So many on DYL they ran out of parking tickets on one day!
The key to unlocking the special and secret places are within OS maps. Park for the Night is often useful. And...controversially, don't share your gems. Let others seek and explore for themselves. There is nothing like that feeling of 'well, how dud we find this?'