Securing Outdoor Pens

[Grond]

Just redesigning my outdoor tortoise pens and wanting to make them bigger.

I've always kept my torts in a locked enclosure with a fine mesh roof up until now, to prevent theft/predation. The current enclosures are about 4 feet by 8 feet.

I'd like to do this again, but as the new enclosures will be about 6 feet by 18 feet, I'm having an accessibilty issue. The only way roud this would be to build the mesh screen in sections and individually lock each one!

Anyone got any clever ideas or pics of ways round this?

I don't want to not be able to get to the torts if I need to, but having 4 lids per enclosure each with a seperate lock seems a bit extreme!