A bit of feedback...... a few plants are in the greenhouse in various soils and aspects.
One is in an internal north-west household windowsill under a bell-cloche with ventilation, and stood in a small amount of water in a perlite-based soil, and in a small, 3 inch, regular-dimensioned pot. That plant indoors has not been subjected to very high temperatures. However, it is doing by far the worst and may now be almost dead after 2 weeks. I think this must be lack of light, or possibly lack of airflow under its cloche. I'm going to move it into the greenhouse shortly to see if it prefers it there.
The other plants are in the greenhouse on the tray system, which has been over 30C most days since they have been in there - we are having a heatwave. They all get very good light and the vents and door have been open as much as possible, and are in a few different soil mixes, all very open, and all in long pots. Two are not thriving but are not dying - just sort of sitting there grumpy. The third is growing. The only difference for that third one is that it is in a long clay pot with no draining hole (the idea is that the clay will percolate enough water from the tray to keep the soil moist while never getting wet) and has a little more dappled shade, especially on its pot. I think from this that cool roots may be useful for the plant - the clay wicks water away and cools the roots via evaporation..
I will feed back any more brainwaves I have based on what I see from these plants over time.
(It could all just be random based on varying levels of root discomfort during shipping and transplanting!)