I am not the most experienced real estate investor only investing in one home in my life, however I have over 16 years in the Lease to Own Business and am currently a Regional Manager for the nations largest furniture leasing company, and deal with similar issues with customers and It has been my experience that in every case the need for something outweighs the individuals need for security and privacy I have on occasion dealt with folks that have initially refused to give a social, however when it came down to not getting the merchandise they always went ahead and gave the info.. 

Just closed on a deal Friday with a seller that cussed out me and my partner on multiple occasions, called randomly late at night while she was drunk to call us criminals, tried to sell the house to another investor while we were under contract and then at closing brought a fishing license as her form of ID.And just like you I'm going to sell the property and put an easy $10k in my pocket.

Plus, saving time on things as miniscule as keystrokes and digitizing data become huge deals that only quality software can solve.A few times, I approached the owner (and on separate occasions, the management) of the company suggesting their development of tools for real estate investors since this industry is focused entirely on every other type of real estate professional except investors.

Use invitation type envelopes (a little more expensive but worth it) and birthday stamps or flowers or animals etc, or some type of occasion stamp.

I would hire an attorney service to pull the data or on occasion a "legal newspaper" will have it.In reality this group is a sub group of absentee owners so if someone is marketing correctly they're touching this group anywayAlso search newspapers and CL for property for rent to find active for rents.

I've had on several occasions been ask for the trust areement which I gladly supply.

Since Old Man Murphy (of law fame) and I have met on too many occasions, I'm big on systems that put the odds in my favor. 

But, I feel this is completely inappropriate given the somber nature of the occasion.

I think the OP is suggesting that the deal was found through the illegal use of these signs, which is the case in the vast amount of occasions when they are used.Personally, I have a problem with it as most know.  

I have had occasions where I have given houses away free just to get them off of my hands because they did not turn out to be a good investment just lucky I had others that did pay me well and I was able to keep going.