Sounds and probably is a silly question.
Do rooflights fit ON the rafters or between them.
Mine are 16" -18" centres of truss roof construction style call 'FINK'
If the roof light can be put on the trusses not between saves a problem needing to get light and air into a bedroom of bungalow with outside window in conservatory [only way to get a decent sized conservatory].
Roof tiles are Bold roll interlocking over felted rood. The narrowest opening outward would be able to see edges of trusses but don't bother me.
Many thanks to responders for comments good or bad.