1. Make invisible to Windozes.
How do you do this ? AFAIK there is no Windows utility which can wipe a HDD in such a way that WinUAE accepts it afterwards.
2. Start WinUAE -disablehardrivesafetycheck
This makes step one obsolete.
3. Mount PC drives at startup.
That's nonsense. This option only adds drive letters as virtual HDD directories. This is nothing you can use to prepare the drive for an Amiga. You have to use the "add harddrive" button and choose the right HDD.
If I make it visible to Windoze, it shows, but WinUAE crashes win I try to format it.
You cannot format a HDD directory. Only real HDD partitions can be formatted. However, WinUAE should not crash anyway.
I am assuming HDToolbox is SCSI only as nothing ever shows up to it accept SCSI drives.
That's not true. HDToolbox only scans one driver. The driver's name is specified in the icon information or by command line. The default is scsi.device which WinUAE does not have. This is the reason why nothing shows up on the first run. You have to change the driver name to uaehf.device. Either open the icon information and change the tooltype to read SCSI_DEVICE_NAME=uaehf.device or run HDToolbox from a CLI/Shell window with the command line
hdtoolbox uaehf.device.
Bye,
Thomas