Really nice assembly you've got going there!
I just did my first Duna trip (my 2nd manned interplanetary trip, and my 1st with a lander) and was so paranoid about missing my launch window, I just started hurling all six pieces at Duna as quick as I could.
At the end of the transfer window it took like 50 days of injection into parking orbits for all the pieces to trickle in.
They arrived with like 10% of their combined fuel capacity left, which I had to scrape together into an ore extractor to start mining Ike for refills.
Six transfer orbits:
https://i.imgur.com/y0e5RC8.jpg
Assembled station:
https://i.imgur.com/9dCzDc0.jpg
First refuel trip:
https://i.imgur.com/T2XEBKb.jpg
Finally on Duna:
https://i.imgur.com/HvWwIiX.jpg
I think I'll be drawing on some of your designs next time around...