Roof hatch idea

[lamb125]

Thinking of removing the hi-top on my van, it's an unfinished blank canvas, i.e. no lining, no windows, just plain fibre glass. Anyway, what I'd like to do is fit a sunroof into the approx. 4 foot x 4 foot hole that was cut into the roof for access into the hi-top roof space. The alternative idea is to leave the remaining raised square surround and somehow fit a hatch with a lip to ensure a water-tight seal. Basically a 4' x 4' lid which could be either fixed down, or made to come off for open access. Any ideas?

[Oldiebut goodie]

The best roof height is 12 foot,.
And i have no idea about the ceiling,.What is its height with ceiling,.?

but forgot his links!