A wide range of sizes are available for porch awnings, because the actual length of the caravan is not important. All you need to consider is the straight, parallel length of the awning rail, and any awning that doesn't exceed this will fit, although it is best to look for a size that will accommodate the door (allowing for clearance if it opens out towards the rear of the caravan) and also without going across your acrylic window at the point where it abuts the van.
Bertie.
Isabella offer a good quality awnings, the Minor porch is quite roomy inside, 2 chairs, table and a dog. easy to put up, carbon fibre poles. They are pricey but very good.
We have an Isabella Magnum porch awning. Very well made, although one zip has prematurely become a problem. And pricey too. In hindsight, I think we could have got better value for money had we searched around more.
Bertie.
We have a Apache Windsor awning, got it 2nd hand but its in fantastic condition, its of excellent quality and I feel it equals the quality of any other major brand. It has lots of features too, I chose it as it has a different shape to the front as its a rounded curved shape. Im not sure if these are still available new but a quick online check should help you.
If you want good advice on what will suit your van try jeff bowen awnings I have previously purchased from them and found them to be very good
------------- its our imperfections that makes us perfect