Here's an update on my search...
Seems I can daisy chain (connect) a wireless router to another router. (See netgear article). I would need to turn off DHCP addressing (so the 2nd router won't issue IP addresses). The second thing I need to do is assign the 2nd router an IP address outside the range used by the 1st router. Seems straight forward.
But sales people suggest I probably shouldn't stick a wireless access point on someone's LAN, behind their firewall. Good point. A work around is to use MAC addressing (assuming PDAs can do that) to limit the wireless router to communicate only with the one PDA. Still I'm sure the client's IT folks would have a bird.