LR - that's right, ICAO does not force member states to validate foreign licenses on their own reg planes. It merely suggests they should
You will find groups around N-reg planes around the place but they tend to be made up mainly of IFR pilots. After all, the most common driver behind N-reg is the FAA IR. But few will accept a fresh PPL. The planes tend to be good ones and while a clever PPL can easily master say a Cirrus SR22 or a TB20 in a few tens of hours (or less) that represents a fair bit of money for you to spend flying dual. I used to rent out an N-reg TB20 so I am somewhat familiar with the situation.