By coincidence I was just checking the dimensions of a Lyen-type controller and a BMS this morning... both have a similar sliding case with inner dimensions of ~ 72 x 140 x 32 mm. With 78 x 145 mm at the moment we are very close, but a further reduction of a few mm in each dimension seems difficult. For the testing of the first boards it's maybe better to leave it as it is (works well for me!). Of course the future optimisation for a cheap chinese controller case would be nice, maybe (if waterproof) suited to be attached to the front tube.
What disturbs me... this mounting hole really hurts a bit... nowadays they attach loudspeakers with velcro to walls...
Modified Scott Nitrous, 74V, MagicPieV2, waiting for Lebowski-Controller by whereswally
Quantya Evo1 and eScooter vRone, each with Lynch motor, 74V 40Ah, Alltrax AXE 7245
Dream: Quantya with Lebowski-Controller and brushless motor (Revolt RV-160, Colossus, Emrax 207, ...)