You can configure a lighter-weight setup (lxde, xfce, maybe mate, mint) so that it writes only if you do some writing. And also mount options to cache for a minute or so, for the smaller writes. But you better have some RAM then, for Firefox in memory/tmpfs. And compiling larger software will destroy your stick.
Also keep in mind, that thumbdrives are relatively cheap is, because it's flash memory is one step in quality before defetctive. Also no wear leveling.
