You have again said ‘recreational area’ four times in your post.
As I have said multiple times, there is no such thing as ‘a recreational area’ in the A16 OA or any other relevant document / legislation.
A3 is an option, but unlike the A3 subcategory which requires 50m horizontal separation, the A16 OA allows flying within 30m of uninvolved people (15m on take off and landing). This is like a bubble, you can fly over them. (Unlike A3 which is a horizontal distance).
Examples off the top of my head (at 1am!):
Flying a drone from agricultural land (e.g. a farmers field).
Flying a drone from a racecourse, on a non-race day.
Flying a drone from a cricket pitch, on a non-match day.
Flying a drone from a football pitch, on a non-match day.
Flying a drone from a flood plain (council owned land, reserved for a river to overflow on to when required).
Flying a drone from a deserted car park.
Flying a drone from the top of a mountain (most likely agricultural land, as above - or possibly a national park. Certainly not ‘a built-up area’).
Flying a drone from a valley / river bank. (Possibly agricultural land, as above - or possibly a national park. Certainly not ‘a built-up area’).
Flying a drone in a forest.
Flying a drone from a private airfield (with permission of course).
Flying a drone from a derelict industrial site.
Fying a model aeroplane above 400ft from a farmers field.
These are just some possibilities. The wording is ‘a suitable area’ and that is defined as ‘anywhere except a built-up area’. So it’s really anywhere you can think of!