USB KVM with DDM and no Display or "V"

I would like a KVM switch with DDM (without the “V” / video) to use for switching my QMK keyboard and Logitech G600 mouse between my Windows KVM in Looking Glass and my Linux host. (I’m currently using Input Leap for software KVM but there are times when Windows is doing things and waiting ~10s for the input to switch to Linux.)

I managed to obtain a used Startech SV231USBDDM for 40 GBPs but if I plug my QMK GH60 into the HID port the Enter key will often end up just being held down and a second press is required to release it; which is just not usable (it doesn’t do this when plugged into the regular USB port on the KVM). Sometimes the G600 stops sending any buttons but does still send from mouse movement, but that’s not too much of an issue as I can just press the reset button on the KVM.

I don’t want to buy a second L1T KVM when they’re 300 USD+P&P (to the UK) when all I need is the USB DDM part of it… Anyone have any recommendations for alternatives or even just a KVM that won’t pass QC on video output but the USB will work or something?

Oooh, you have a 4 port KM switch… are there any plans for a 2 port?