Hi Joe welcome to the site.
Its difficult to put a figure on how many, I would guess at over 50%, as for guides only one that I know of puts lengths in; and that's The Big Pitch Guide, or pay a tenner, join the club and you can search the campsite database for RV suitable pitches.
Just had a look and 409 are shown as suitable, that generally means they can take over 30' so you would be well in.
Olley
Just had a look and 409 are shown as suitable, that generally means they can take over 30' so you would be well in.
Olley