Hello from two 26 year old Aussie travellers!
Seasoned Morocco experts, please let us know if you think we've allocated the correct amount of time to the below cities on our 9 night / 10 day Morocco trip? All of these places are a must for us, but at this stage the only thing booked in is our flights into Marrakech and out of Tangier, so am open to suggestions! We are absolute energizer bunnies, we don't stop, so don't fear that we will be rushed - we get up at 6am and don't retire to bed until midnight while travelling so we will have lots of time to soak it all up
The Desert Tour in bold is with Morocco Desert Tour.
They seem well reviewed, but please sing out if you think there's better tour companies!

Aug 26 - Land in Marrakech 12.40pm - staying at Riad Kasbah & Spa
Aug 27 - Marrakech - staying at Riad Kasbah & Spa
Aug 28 - Marrakech - staying at Riad Kasbah & Spa
Aug 29 - Marrakech – Ait Benhaddou- Ouarzazate – Rose Valley – Dades Gorge
Aug 30 - Dades Gorge – Todra Gorge – Merzouga – Erg Chebbi
Aug 31 - Erg Chebbi – Merzouga – Midelt – Fes - staying at Riad Fes Baraka
Sep 1 - Fes - staying at Riad Fes Baraka
Sep 2 - Fes > Chefchaouen - staying at Casa Perleta
Sep 3 - Chefchaouen > Tangier - accomm not found as yet, suggestions?
Sep 4 - Depart Tangier at 2pm

You must know that most parts of your itinerary will be warm, likely 90º-100º F (35+C). (Travel Weather Averages (Weatherbase)
Chefchaouen & Tangier will be nice.
It's too much in too little time for me but you've addressed that already, though heat + speed can be a not-so-great combination.

That leaves accommodation in Tangier. La Tangerina is where I stay, great location (at least I think so): LaTangerina hotel

Yes, we did consider the heat, but we've been through Europe (Spain, Italy, Greece etc) in August before and survived - and actually enjoyed the heat! August is the only month that works for both myself and my partner each year, so we have come to expect and embrace a warm trip.
As Tangier is the only stop we have no major interest in visiting (we are simply flying out of there because it was the only direct flight out of Morocco to Madrid that day), perhaps we could get a driver to drive us 2 hours to the airport from Chefchaouen to Tangier on the 4th so we wipe out Tangier and get an extra night in Chefchaouen instead?
I would consider adding on an extra night to the Erg Chebbi desert tour instead of Chefchaouen, however from all the trip reports I've read from those that have done the organised tours through the desert, they seem to think the two night / three day trips are enough.

It took me a number of visits to Morocco to finally make it to Tangier and I wondered why it had taken me so long. Chefchaouen is pretty but otherwise fairly dull. But I suspect from your posts we differ in just about every measure of travel style & interests, which makes perfect sense, you're 26. So this is where I sign off and I'd recommend you give Lonely Planet Thorn Tree forum a visit too, if you haven't already, a younger crowd in general: https://www.lonelyplanet.com/thorntree/welcome