There is a company that will print you postage with images (they aren't really stamps but work like stamps and are legal).
Might not be a bad idea (but they aren't cheap). Alternate method. Get some Fitzmas seals printed on put them on all your envelopes...
That is Freeper Seeking The Truth's company....www.ocents.com
That company that prints the custom postage was originally just screening the designs that people submitted for porn and such ,,, until someone had 1000 stamps made of Kazinsky (unabomber)... they didn't catch it but the USPS didn't think it was too funny...
Some joker ordered batches of stamps with the Boston Strangler, Julius & Ethel Rosenberg, etc. To avoid future embarassments, they now have more limits on what they'll accept.