XMcShiftersonX, I had an inkling you were talking about Marymoor from your initial description!

It is super-popular with families and I think that will be hard to change. It sounds like you have the right idea with being proactive about Megatron's behavior if a free-range child comes into view.

I also feel that when you are in the off-leash area, it's completely appropriate to coach people how to interact with your dog, if they indicate that they want to. The park is well-signed so presumably they know they are going to encounter dogs off-leash! Especially if they are also bringing their own dog.

In my dog Gordy's case, I tell people he can be a bit shy and nervous around new people, so they should just let him sniff their hand and then scratch him under the chin if he comes to them. If I have treats handy, I will show them how to ask him to sit and then reward him with a treat.

Maybe for Megatron, something like "he doesn't know his own size . . . " to break the ice, followed by how you would like people to interact with him for a positive encounter.

It's too bad we don't live in Seattle anymore, because Gordy gets along with larger dogs really well. I bet they'd get along really well!

I would also recommend checking out other dog parks in the area. You might find one that doesn't have so many kids running around, and you would still be able to get that interaction with other dogs that is important.