The smallest tray I have seen in a dwelling is 760mm square.
Mobile Home fittings may in fact be smaller than this.
This is a matter of physical size and usability.
ONQ
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All advice on AAM is remote from the situation and cannot be relied upon as a defence or support - in and of itself - should legal action be taken.
Competent legal and building professionals should be asked to advise in Real Life with rights to inspect and issue reports on the matters at hand.