I have really never heard complains about Google AdWords having a limit on the characters allowed in the display URL. Today, I found out that the max number of characters you can have in your AdWords display URL is 35. An advertiser ran into this issue and posted the details at Google Groups.
I suspect this wasn't much of an issue before Google began enforcing the display URL policy. Back then, I assume you can use shorter versions of a domain name and get away with it easily.
So, what do you do if you really need more characters in your display URL?
(1) Drop off the www, preceding the host name. I.e. you don't always need www.seroundtable.com/pagename/, you can drop off the www in many cases (especially for the display URL).
(2) AdWordsPro suggests that if those three extra characters don't help, then you should contact an AdWords representative. It seems that maybe Google can either aid you with your issue or bend the rules a bit.
Forum discussion at Google Groups.