As to your original question about the Phals staying alone for several weeks, I do it every summer and my conditions in the Netherlands sound similar to yours. No AC, and it's usually 24-30C indoors in the summer. I go on vacation for 3 weeks in July/August and when I get back the plants look fine. They're really dry, but I rarely see wrinkled leaves. Even the Dens and Paphs are fine.
What I do:
- Water the plants really well the day before leaving 5I do a mong, several hour soak).
- Move them all to the coolest room in the apartment, curtains drawn.
- Each plant had a saucer under the pot, these are all filled with water, which keeps the plants hydrated for the first week or so (usually empty within 3-4 days, and takes another 3-5 days before the plants are completely dry)
As to the mealies, I've been dealing with them for 15 years, never completely got rid of them. I do a mealy treatment (neem, or insecticidal soap, or wipe down with rubbing alchohol...) before leaving, and I know that I'll have to repeat it once I get back from vacation... There are definitely more mealies than before vacation, but they do not take over the plants.