I have never been happy with the roof on this model maybe I’m picky but it just didn’t look right. After thinking about it for quite sometime I thought I would experiment with 10 mm wide yellow Tamiya masking tape it is sold with a dispenser. To begin with remove the roof vents with care they are a press fit so be aware and put them in a safe place next cut the tape 45mm in length then narrow it by .5mm to 9.5mm with a scalpel on a gloss surface like a mirror or tile, that will be just right to stick it between the raised cross section. After sticking the masking tape in place make sure the tape is pressed in along the roof gutter then by using a scalpel carefully trim the excess tape and repeat the process until you are happy with the result, like me it may take 2 or 3 goes to get right.
After you are happy with the result with care replace the roof vents,mask the van sides and both ends then prime the entire roof black and weather to your liking