Of course it's doable. It does require some skill. I found it tiring and somewhat stressful (especially after many hours), but ya gotta do it so suck it up and get 'er done. Some tips based on recent experience on these very roads...
The driver needs to be on his/her "A Game". All the time. Don't drive when you're exhausted, grumpy, not feeling up to giving the task all of your attention. It really requires a lot of concentration, and while that may sound easy (and it may be, for a few minutes), maintaining that degree of focus and concentration for hours and hours does take its toll on you. Stay VERY alert. Give yourself breaks. Offload all non-critical tasks, to...
You need a left-seat copilot. The person sitting beside you is NOT a passenger. They play a vital support role and they need to take their role very seriously - like, deadly seriously (think: head-on collision at high speed serious). Your copilot needs to handle all non-driving tasks - everything other than what you need to do with your hands and feet to drive the car. That includes navigation (GPS and map, physically pointing to and calling out every turn, referencing signs, providing you with advance warning of everything coming up, double-checking the driver clearly understands, etc). They need to help you navigate all the roundabouts. They should regularly (maybe constantly) remind you to "drive on the LEFT" (especially after making a turn or doing anything other than just driving straight ahead). They should be scanning the road ahead on narrow roads, warning you of any oncoming wide vehicles (farm tractors, trucks, and yes, tour buses). They also should give you frequent "spacing checks" - giving you feedback on how close to that stone fence at the roadside you are, how well you are centered in your lane, and general encouragement. They should check on the driver frequently - are you OK, need a drink of water (done very carefully if at all), need anything else? The copilot job is critical and they will be as busy as the driver.
I did all the driving on a recent trip and after one particularly long day in the saddle (started in Galway, drove through The Burren, the Cliffs of Moher, all the way to Dingle), I was completely wrung out and wasted. I did it safely and carefully (I've done a lot of driving overseas, including plenty of "opposite side of the road" driving) but when I finally peeled myself out of that car in Dingle, I was so glad to be there I nearly kissed the ground (so did my copilot spouse). And this was in a very small car. Honestly, I wouldn't want to do the same drive in a 7-seat SUV....you need to be super super careful.
Start very, very cautiously. The first 15 minutes of driving in any foreign country are the most dangerous (and terrifying). Ease into it. Stay sharp and demand help from your copilot, and be sure someone else keeps everyone else in the car under control to minimize distractions. They are not allowed to get "wigged out". If anyone starts to get "wigged out" then you should stop and let them get out and walk the rest of the way (because noise and distractions from the back seat could get all of you killed). Everyone with skin in the game (anyone in the car) needs to be on-board with the plan, understand the stakes and cooperate. It's serious stuff.
Good luck!