Campervans are generally small and don’t have any bathroom facilities, so you would need to stay on a site, of which there are plenty. A motor home is larger and has bathroom facilities. Wild camping in a motorised vehicle (as opposed to a tent) in my experience is becoming increasingly difficult in Scotland. Many councils are introducing local bye laws prohibiting overnight stays. Water acquisition and disposal is an issue if you don’t stay on sites, plus you don’t want to be carrying lots of heavy water around as the vehicles are uneconomical enough to start with!
You will find that hiring a motor home plus site fees is likely to be more expensive than hiring a modest sized car and staying in hotels, apartments or B & Bs, plus a smaller vehicle is better for negotiating the narrow Scottish roads than a larger vehicle.
You may find restrictions on taking a hire vehicle on ferries.
I spent a month touring round western Scotland a few years ago in my caravan. We didn’t have time to get to any of the islands, other than a day trip to Orkney from John o’Groats, which was worth doing, but the passage back was very rough. I was there in May/June and the weather was very mixed - one day only got up to 7 degrees! It was 28 degrees that day in London. The campsites on Skye were all fully booked, even in late May. We prebooked all the sites, luckily, as many were full.
I would suggest that in a 2 week timeframe that you consider how much ground you can realistically cover. If using Google Maps, add a third or if allowing time to stop for scenic photos, double the time including comfort breaks.
We didn’t do any whiskey tasting - horrible stuff. I only know one person that drinks whiskey, but it seems to be a popular thing for foreigners to try. It’s difficult when one person has to drive.