Not easy.
Say six apple trees per trough, on M27 preferably. perhaps M9.
M26 is too vigorous for such a small rootspace.
And yes, the most dwarfing you can source for other fruit trees.
You will need to water regularly in summer, so plenty of maintenance. M27 is better because trees crop even in the first year, or better from the second year, whatever – this is not a project to grow ten year old trees, I reckon five years max. Hope I am wrong! Best of luck.
