with the top of our door - when putting away - we found that by getting one of those $2.00 straps and tying it up before hooking up to the roof always worked

held the outer edges and the center together in an easy unit to hook up and put away
as for folding the canvas - great fun
you can leave the sheets on if you want - but not your doona or pillows
the bed ends, I used to drop the hockey stick, and pull the outside corners into the middle, then undo the velcro underneath and tuck the sides in, then push he bed in, as your pushing the bed, just make sure it folds in towards the middle and as far into the van as you can
(some one small inside pulling the canvas also works

)
try to get the canvas to sit as much as possible in the center
then
when winding it down, go half way - make sure the sides are folding inward (quick wander around van easy) then continue until about 5 or 6" to go, and again, wander around poking with your hand any canvas not sitting right.
the corners are the hardest to master - make sure your curtains are in the middle, and try and get as much of the canvas to sit close to the middle when putting down.
you will notice - there is more room in the middle than the sides (bowed roof line)
takes practice, and more practice (good excuse to go away on the weekends)
I watched a Truckkie trying to fold one like a Tarp - undo the beds - push in then fold canvas like a postage stamp - to each their own
you have to work out what works for you - and is easy enough - not stressful.
cheers