Won't fit with my trailer on which mounts to my seat post. I currently have a frame bag setup but want something tidier. OCD reasons mostlyPut it in a toolbag under the seat, which is much easier.
Was thinking about a box but a 6 fet case barely fits in my frame let alone a 9, only way I could think is to mount it on the downtube with some kind of clamps, top tube is another option but it's a square shape so the original brackets again might not work great. I found a kt controller with the waterproof plugs that is painted black and would look really nice just mounted as is, just hard to mount something that doesn't have any hardware to mount it. The rectangle bags like cyclotricity sell are pretty stealthy so that may be another optionhttps://www.ebay.co.uk/itm/Small-Big-Size-Electric-Bike-eBike-Moped-Scooter-Controller-Box-E-Bike-KIT-Case-/401688265530?vti= try this style cheap and works but find a uk based seller