Ok I love the idea of Clan Tournaments and would love to see this implemented. Let me add a few points/potential issues. You guys may have answers already but I'm just trying to think from all angles so this becomes a perfectly rounded proposal
The basics all seem spot on, 16 teams, 4 wars, 1 winner. I also like the idea of 1 prep day but see a few issues here. Firstly, if they were to use a matchmaking system where a war starts at a specific time how do they decide what time this is? All clans want the war end time to be at a time their clan is most active this will be hard to tailor to all. However as previously stated other ways to bring 16 clans together could take ages! I think I may have an idea for this... So I see it as a second option you can choose after tapping the current clan war button, once in this menu you'd see "start war" and "start tournament" if you select "start tournament" you can then choose a start time from say 4 options all 6 hours apart (this would require some research and may need more or less time options, and some SC tweaking for best times), then it works like joining a poker tournament online, you'll see a list of clans filling up until it reaches 16 teams, these teams will have been pre matched using the matchmaking system to ensure teams are of similar strength. So once your lobby reaches 16 it starts at the next available start time you designated. Yes it may take a little longer but I'm sure we would all prefer to be in a war with a start time that suits the clan we are in.
Also the 1 prep day would mean if I was filling 20 spaces in a clan castle with one dragon, for example, and this stayed in that cc all the way through the tournament, I have potentially saved 75% what I'd have had to pay filling the same cc in 4 standard wars. This would be too much of an incentive to never do normal wars again. Because even if my clan only wins two wars and loses in the semi finals I've saved 66% on Dragon expenses. This could affect the amount of clans being able to find normal wars as so many others will be using tournament. And some clans may not be able to commit to a full 4/5 days warring and may wish to stick to normal wars, that's a little unfair on those clans. As much as I don't like the idea of the tournament taking 8 days I think it would be better to have a prep day still between each round. A lot of clans spend hours devising tactics during prep days so to win in round one and the quarter finals to start immediately could be a bit too full on. Plus the potential win bonus being made by each player within the proposed structure of a 5 day turnaround would mean far too much loot making upgrades much easier to purchase.
Remember SC structure the game to make money, they want people buying gems, if there is the potential to make 4 wars worth of loot in just over half the time it normally takes PLUS a tournament bonus then it probably won't be a viable option to them! just as an example, in my last war I made 600k loot, if I won a tournament and made that in each war I'd make 2.4million plus your proposed tourney bonus, let's say 50% that's 3.6million in 5 days (1 prep and 4 wars) that would currently take 12 days plus war search time in the standard structure.
I think this idea is brilliant i just feel it's unlikely to work with the current set up. It can work it just needs a lot of tweaking!