I used a 64GB USB 3.0 stick for a limited time until I upgraded to a 2,5" HDD, and seem to recall it working well.
It will. The decay of flash media is grossly overstated.
There's some crappy outliers there for sure, but they'll normally get anywhere from 3k-100k writes before dying depending on tech. Given that in this scenario you're writing once and just reading from there a quality USB stick should be fine. There's plenty of cheap choices that will hold more data than you need and completely saturate the Wii-Us usb.