Hi,
Yes. WinUAE would be the better and faster method. Just get a SD Card reader (USB) type. Place the original SD card in and you can boot with that on WINUAE.
Then place the other SD card (32GB) in the SD card card reader.
The best practice would be.
1).. Get the 32GB card. Place in the card reader. Then using CMD command with Administrator rights type without the following without quotes “Diskpart” press return.
2).. Then “ list disk” press return. Check on the list it sees the 32GB SD card. As the next bit will destroy data! So pick correctly or you may wipe the wrong disk!
3).. From the list use the command “select disk” so if your 32GB is showing as disk 3 you use the command “select disk 3”.
4).. Run “List disk” and check that an * is next to the correct disk.
5).. Now the dangerous part. Making sure you have selected the correct disk. Type “Clean”. This will wipe the contents of the disk selected. This should have been the 32GB SD card.
Now you can either place that SD card into your A1200 with a bootable 3.2 Install disk to use HDTOOLBOX to prep. Or WinUAE booting off the 8GB card and using HDTOOLBOX to prep and format the 32GB SD card.