They also say which height of vans they will fit our new Kampa Rally 200 fits vans 235-250 cm so you'll need to measure the height of your awning rail to the ground.
When we changed from an FC to a Caravan, I measured the drop from the caravan awning rail to the ground and then measured from the awning bead to the bottom of the wall of the porch awning.
There was only one inch difference so perfect fit.
We have a Pursuit 340/4 and purchased a Ventura Merlin which fits perfect from side of door to just past window over bed. Remember the porch awning size is the footprint and may be smaller at rail height.
That's the ne that I've got and it went on my Conway Cardinal and now my Coachman Pastiche 420/2. It's a really good awning and I've also got the canopy one as well.
I would say go for a large porch awning . We have spent a lot of money on awnings in the past they never seem to fit the next caravan. We have recently bought a large porch conventional type . It's brilliant .and we know if we ever change vans it will fit the next one.