Unless the top tube is perfectly horizontal, a pump/pump peg is gauche. Either put it on the seat stay, hide it in a bag, or use a mini-pump mounted at the cage.
I just built my dream'ish bike ... Routt 45 with rack mounts on the mono seat stay. Three bottles, Di2 GRX with internally routed wiring in handlebar, hydro discs, and Barlow Pass 38 Extralights on Belgium Plus wheels. Fenders are still TBD (hidden mounts) as I'm currently shocked at the $45 shipping for a set of Rene Herse and will be putting some old plastic Planet Bikes on for now.
I didn't do a coupled bike, as I have a Ritchey Breakaway and a 29er MTB, and those have got lots of scrapes and dings over the years of travel ... I don't want to scratch the forever bike.
Only thing I think I'm missing is a front rack. There are a number of carbon bikepacking forks out now, and maybe by next summer I'll look at supplementing the stock fork with something I could put a porteur rack on.