OK, then I would doubt it's an encryption or WMM issue. Don't mean to ask a dumb question, but you're sure WiFi was turned on in your iPad under settings? Where you picking up any other networks? In any case, you could try resetting the WiFi on/off or renewing lease, but doubt that would fix the issue of not detecting the WiFi signal. This is where a sniffer app would help, but apparently, not a readily available option.
My other thought would be that it's simply the built-in WiFi receiver antenna combo is too weak to pickup the signal. I've noticed at work that my iPad's WiFi connection will drop out at one area though literally within 20 feet of the router. It seems not to be as tolerant in maintaining a WiFi connection when it reaches a certain threshold. Eventhough my smartphone will maintain the same connection at that signal strength. Apple "may" be able to boost the WiFi receiver's Rx power through an iOS update, though will use more battery power, but that's certainly not in your control.
The only thing I can think of off hand is to get a separate router with repeater capability. You will likely have to configure it in some minimal way at each Park or CG you visit. For instance, inputting the Park's SSID and password allowing the repeater to auto login to the connection, and re-broadcast a stronger signal for your iPad to pickup. You should be able use your iPad's browser to configure the repeater.