Sid

I gave up and buy shampoo at the destination. A small bottle is a couple of euros anywhere in the world and I leave it behind. Not a solution if you're going somewhere remote, but for cities it removes an entire category of packing decisions.

Is the rod swap something a reasonably handy person does, or is this a plumber job?

Did this at the weekend and the smell is gone. Will still do the anode when I get a socket set that fits.

Shower rail is the deadest air in the room. Put it on a hanger and hook it in front of the AC unit or the ceiling fan, ideally with the hanger turned so the shirt hangs across the airflow rather than edge on. If the unit has a dry or dehumidify mode, run that instead of cooling for a couple of hours before you sleep. Moving air beats warm air every time with wool.

Then 40L and be done. A packable daypack is 90g and 20 quid and covers the four-night stop.

Decide it on how many nights you sleep in each place. If you're moving every second night, a single bag wins because you never repack two systems and nothing gets left in the other bag. If you have two or three bases and do day trips out of them, the 20L plus daypack is much nicer because your day bag isn't a half-empty 40L flopping around. For a Lisbon to Highlands trip with a warm layer, I'd take the 40L and a 10L packable that lives in the lid, and skip the third bag.

Stop packing the front pocket with anything solid. On almost every soft pack the front pocket sits outside the frame, so a charger brick and a pair of sunglasses in there is what turns 20cm deep into 24cm deep. Move all of that inside the main compartment against your back panel and the bag goes flat again.

Right up until you have dinner with the same people three nights running, which is why the button-down earns its place. One collared thing that looks intentional covers every situation where you'd otherwise feel scruffy.