It seems a good way to corrupt your Clonezilla backup. USB drives are now extremely cheap. You can get a 32 gig for as low as $5 bucks from Office Max/Office Depot.
Why take the chance?
If you decide to partition, make sure the partition you format is FAT32 or xFat
If it was me, I would open gparted, find the pen drive, delete the partition, lay down a new DOS partition and format it to FAT32.
I now you don't want to spend a lot of money on this, but I will ad one thing, an external hard drive is multiple times faster than a pen drive if you have a lot of data to transfer and you want to do it quickly. The first external hard drive I bought was $100 for 250 gig and I still use it. The second external hard drive I bought was 1 terabyte for $100 and I still use it. You can by a 3 terabyte hard drive for as low as $30 dollars at Office Max. I find that amazing as my first 1 gig USB drive cost me $99 dollars. Not saying you should, but it will really increase your transfer speeds if you do.
Not only does it support USB 3.0 data transfer rates up to 5 Gbps, but its UASP (USB Attached SCSI Protocol) feature reduces latency and allows it to perform up to 70% faster when connected to a UASP-enabled host controller. Perfect for storing and sharing large files like photos, music and video files,
Just giving an example of what you can get (multi-port USB extender) which would allow that 1 port to serve multiple devices attached to the other USB ports.
I am sure people are happy for you, but this forum is about solving Ubuntu Mate OS problems. I am happy you got your problem solved but felt no need to comment on that.