my pendrive is 8Gbyte.
i did try to install dvd opensuse 11.4 64bit in my pendrive: works perfect but size is 4,4Gb…
suse studio imagewriter:
-dvd opensuse 64bit and cd opensuse 11.4 32bit in pendrive…totale size 5,1 (4,4Gb + 0,7Gb)
Maybe you can not install the same operating system with two architectures in the same USB stick.