with only heat from the bed I got to 50-60C within chamber and you could barely feel heat coming out of the upper and side slots ("plastic melting smell" zone is also reduced - 2-3m vs 30cm from printer). I guess it's due to absence of holes in the bottom of the chamber so no place to suck cold air from and no convection. The is always an option to put rubber seal - lip like contraptions within those slots but i don't think it will be necessary unless you direct some external airflow into them.
Also executing fume venting or filter is quite easy.