5th gen light fighter. is it practical?

There was a convo here but I forgot from whom.. probably DJ Cross..

about a discussion that a 5th gen stealthy aircraft could never be light
The need for an internal bay, larger internal gas capacity, room for sensors, etc
end up creating an aircraft that will end up being at least a medium..
the F-35 being borderline heavy.

is a 5th gen stealthy gripen sized aircraft impractical?