Clearly you arrange a time and she gives you the venue (name of the park) by email. You then arrive at the park and wander around calling out 'Panda', quite safe and won't raise any suspicions because most people will think you've lost your dog and it's got a silly name.
Having met her by the swings and after allowing her to finish her Red Bull n Vodka you proceed to the bushes for a half hearted blow job . Go back to the swings for a break and then back to the bushes for round 2 - a nice bit of bareback banging. Have a quick dip in the nearest river or lake (if it's a posh park) and then off home.
If anyone then enquires about the lost dog just say 'I did find one but wasn't quite what I was looking for'