More than that means radio and transponder or some very convoluted routes.
Radio: yes. Though I know some... who have ... at some time ...
You may be very sure there is a fair amount of microlight traffic between BE and FR with no radio at all, or stand-by listening at best. I'll not say from which BE field instructors would routinely take their pupils to Maubeuge for touch and go's on the hard runway - nice complicated airspace with gliders and paradrop but never a syllable on the radio...
Transponder: not necessarily. I have flown from BE to Germany and France with no transponder, no issues. Though Langen Information audibly raised an eyebrow
"Oscar Oscar ... , confirm negative transponder?" "Langen Information, I SAY AGAIN, negative transponder, Oscar, Oscar, ... " after which the lady came with a very sensible and workable solution.