I had used a Micrbotics Starboard II with SCSI for a couple of years. I now use an old Xetec Fast Trak/ Fast RAM box that is supposed to be A500/A1000. It ends up backwards on my machine with just room for a true A1000 mouse (the one with the angled plug) It works quite well though.
I'm still trying to get a PC board to allow using a newer ROM from one of our German members here. I'll let you all know how that works, if and when...
A500 sidecar boxes work, with the problem of blocking off the mouse/joystick ports.
Nothing is really easy doing this, I guess.