As a new member I'm just finding my way around the forum as time allows and I've discovered this section and thread.
Living in the mid-West of Ireland I can heartily recommend the Wild Atlantic Way. Amazing scenery and locations along the way. If careful about it there are a few spots that one can set up overnight camp at without raising too much attention.
It's a paved route all the way. Off road tracks aren't really that prevalent here in Ireland but there are probably a few hidden gems and mountain routes that are worth a shot.
One of my favourite locations would have to be at Cromwell Point on Valentia Island in Co. Kerry. You can access the island by ferry from Renard Point at Caherciveen or take the road bridge from Portmagee. Hint, bring any supplies you might need from Caherciveen as shopping especially for food items is limited on the island. However there are great pubs serving excellent food.
There is plenty of room to set up camp on the rocky shore near the Cromwell Point Lighthouse as long as you leave the access road clear. Excellent fishing, good diving and a sunset to die for as you look out over the Atlantic Ocean from one of Europe's most westerly points. Its also located in the Kerry Dark Skies reserve so if conditions permit there is some excellent stargazing and nighttime photographic opportunities.
I've been lucky enough to have been able to visit and stay at the lighthouse for a weekend for around the last 15 years but that's another story... Hint, for those of you into amateur radio think ILLW in August...