Specify USB drive partition to install live Kali to?

I've recently bought a SanDisk 64GB USB Drive with the intention to use it both as plain storage accessible from my windows os *and* as a bootable USB with persistent Kali Linux.

I've managed to do that only halfway: I've been able to either first flash the kali image to the drive and then use something like Minitools Partition Master to turn the unallocated space into a second partition, or first create the partitions and then try to flash the image.
However, neither of those approaches seemed to work: If I first define the partitions and then use something like Rufus or Win32DiskImager to flash kali to the drive, all the partitions simply disappear and the installed image is located at the very start of storage and everything else is just unallocated. If I want to now make a new partition for the storage, I have to create it *after* the bootable one, which is fine with Win10, but does not work on earlier versions of Windows, which is very limiting.

Hence, my question: Is there a way, a tool for either Windows or Linux, to flash the image to a specific partition, or at least flash it with a specific amount of unallocated space preceding it?

Thank you very much in advance!
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