If you only needed an enlarger for 35mm something like Durst F30 could be an option. Very small and light.
Since you also want 6x6 you need something bigger. Long ago I used an Opemus (5 or 6 but I can't remember exactly) that was very easy to dismatle for storage, but I suppose any enlarger which is easy to take apart will be a good choice. You only need to be able to separate the base from the column and it will be fairly easy to store.