Your current route implies that you want to take the ferry to Skye ("Portree - stop at Glenfinann Viaduct on the way"). You need to take a couple of things into account. Firstly that this will involve a ferry from Mallaig to Armdale (Skye) and you will need to book the ferry to be sure of getting a place on your chosen ferry . Secondly, that in winter the weather can affect sailings more often than in summer. If you can't get the ferry then you will be back tracking from the viaduct to Fort William and from there it is 2.5 hours to the Skye bridge and another hour to Portree. Daylight is in short supply in late November.
Almost every American I have met (and I run a B&B so I meet a lot!) has not only underestimated the time it takes to drive places here, but also the type of driving. Guests often arrive somewhat traumatised by the experience! Our roads are narrow. They have no 'shoulder' and in the Highlands and Skye you will encounter single track roads with passing places. These are one narrow strip of road shared by traffic going in both directions. You have to pull in passing places to let traffic coming in the other direction pass. You need to familiarise yourself with how to drive on these roads. This video will give you the basics. If you cannot keep up with the flow of traffic and are causing a tailback you also need to pull over to let traffic pass you because you will not want to be driving as fast as the locals.
Anyway, back to your itinerary. It looks as though you are planning for one full day (day 5) in Skye. I'm not sure you will particularly enjoy Skye in late November. The weather is likely to be extremely unpredictable but one thing is almost 100% certain - and that is that it will be wet and very windy. All of Skye's attractions (except Dunvegan Castle which will be closed in late November) are outside. I'd not be wanting to spend a day hiking in late November! So I'm wondering whether you should have a rethink. Do you really want to come this far north and west in late November? Loch Ness is not one of Scotland's prettiest lochs. Yes there is the Nessie connection, but the Nessie visitor centre in Drumnadrochit is tacky even for a 10 year old.
If you want to see an island and take a ferry then maybe Arran (known as Scotland in miniature) might be better as it is much closer to Glasgow. You could spend a night or two there (instead of Glencoe, Fort William, Portree & Inverness) and focus the rest of your time in the Central Belt. This might give you time to also include Stirling (there a fabulous Kelpies sculpture just south at Falkirk) and its fantastic castle, which is great for kids. Also Edinburgh Castle and I'd also recommend the Museum of Scotland in Edinburgh, which has lots of hands on stuff for kids.
I hope this helps. I honestly think the Highlands and Skye in late November could be a recipe for a miserable vacation (and I live here!).