Hey there, I am 6 ft 5 and 185 so we are in a similar situation.
From what you have outlined you are right on track with the Duplex, and yes I actually sold one earlier today. My only concern would be a dog bouncing around on the cuben floor.
I have tried
Zpacks Hexamid long – No longer in production – absolute palace for a tall guy, Ok with an additional short human in a pinch, but in tent mode the claws vs. cuben floor would concern me.
Yama Mountain Gear Cirraform tarp/Borah Bivy combo – I did the whole JMT with this combo and enjoyed all 7 nights. Very easy, and lots of room for one, no second person and no room for a dog This could be fixed with a Cirraform 2 person tarp to compensate for the dog, or the DW version as Gen uses SilNylon for the floor. As soon as YMG gets fired up again I am looking forward to checking out the Terraform in Cuben this could be a cool solution as the vestibule is larger and Gen will make it longer to allow more room where you need it.
HMG UltaMid 2 – awesome shelter with tons of room of room you, a friend and even a dog. As long as you are comfy in a floorless scenario. I actually sold the first one and have repurchased to keep one in the quiver
MLD Trailstar – Huge and lots of room, just not quite long enough for my likin. Amazing do all shelter for most.
Zpacks SolPlex – awesome single person enclosed shelter with cuben floor – At 6 ft 5 I was comfortable most of the time but long nights I found myself wanting more room to "live"
Zpacks Duplex – I bought this for my son and I, and it is a palace for one – I sold it as he is not that into hiking right now, and will probably pick up a Triplex as the 9 year old is all over the place while sleeping, even switching ends half way through and kicking dad in the face. LOL
Ruta Locura Lone peak -like the HMG Ultamid 2 this shelter has a ton of room, but the lack of ventilation from the bottom concerned me. Great in the winter with a stove though
MLD SoloMid XL – this is my current go to now that Ron is making a Long inner for it, unfortunately no room for Dog but the Duomid XL would solve this as the dog could either come into the inner behind the pole, or could sleep intron of the pole just inside the door and still have room for another human without issue.
The Good Old Fashioned Zpacks 8 X 10 Cuben Tarp. This is so flexible, and allows you so much freedom, provided that you are comfortable under a simple tarp. bivy/no bivy, net tent, no net tent…
I do have the New Zpacks Alphamid on order, but I can not comment as I have yet to receive it.
Please feel free to PM any direct questions regarding any of the shelters outlined above.
All the best,
Jeff