News flash: People do not like to be sued. Oftentimes, they know it is coming and they will go to great lengths to avoid service of the summons and complaint.
In situations like this, 735 ILCS 5/2-203.1 allows litigants to accomplish service by alternative means. The question becomes what alternative means to use. I've used this statute dozens of times. I always ask for regular mail and posting at the defendant's residence. Some judges, however, require that the mailing be sent via certified mail, return receipt requested.
You already know my feelings about certified mail (See, Certified Mail is Stupid, Northern Law Blog, January 29, 2013). No defendant in his right mind would sign for a certified letter while ducking service. Instead, I would suggest a counter-proposal to the judge. How about UPS? No one ever turned away a package from UPS. Imagine the defendant's surprise when he tears open a huge box and finds only a summons and complaint in there. I love it!!
Full disclosure: I didn't think of this myself. I saw another lawyer this morning hand up a UPS receipt as proof of service.