I think there's no way to be safe from patents, except to be not worth suing. And since anyone can sue you for anything at any time, so there's no point fearing the uncertainty.

BTW: I've seen a strategy for avoiding patent infringement of a standard by using only 20+ year old techniques. If it was published over 20 years ago, any patent would have expired. Unfortunately, someone could have had a "submarine" patent (delaying issue of it) so you need to wit X years longer, where X is unknown...

Selden did it to automobiles: http://www.bpmlegal.com/wselden.html