I’m not sure where in your itinerary you are allowing time for going on hikes (or museums, apart from in Edinburgh)...
April 16 - That is a lot of driving for the day . You are talking about 250 miles and 7+ hours without any stops to get to Oban. Continue to Glencoe area and that adds on another 35 miles and nearly another hour to the drive time...
That distance may not seem far, but driving in Scotland is slow. It will take a lot longer to cover distances than you might expect. Many roads are narrow and winding. Overtaking isn’t easy.
Are you planning on any sight seeing that day - Stirling Castle, St Andrews etc? If so, forget it as you wont have time, although you will see some wonderful scenery through the car window...
If the loop around Crail and St Andrews is a must, you can make it a more manageable drive by removing Pitlochry. Use the Forth Bridge to do a loop round the coast through Crail and St Andrews and then cut back across the middle to Stirling and then across to Oban. This is about 200 miles but is still going to take about 6 hours PLUS stops.
2 nights on Skye is effectively only a day and a bit. I’d agree with Coffee Girl that isn’t much time and is definitely short changing Skye. Rather than heading for Skye, have you thought about Mull instead? It is easily reached by ferry from Oban and is also scenically very good. Tobermory the main town is very attractive with its brightly coloured houses along the shore. You also have chance to visit Iona too with its early Christian heritage or the delightful Ulva. There are also all the antiquities around Kilmartin Glen just south of Oban.
You could easily fill in the four days based around Oban, Mull and Glencoe. It’s also less far to drive to Moffat too.
What are your plans for Moffat?
If you want completely different suggestions, head to Biggar, just under an hours drive away. Biggar Gas Museum
in the old gas works which used to make all the gas for the town is one of only 3 left in the UK and part of our lost heritage. We found it a fascinating place to visit and it still retained all the old evocative smells! Biggar itself is an attractive small town and the museum is also fun. They don’t get many overseas tourists so will be delighted to see you!
Another suggestion is the Museum of Lead Mining at Wanlockhead - about a 45 minute drive from Moffat. It’s a wonderful drive to get to the highest village in Scotland and one of the most isolated, especially in southern Scotland. It is surrounded by the Lowther Hills - bare windswept grass...