Some good people are stepping up to the plate and are advising us of preventative measures that we can take. I link now to one very informative article from Leo Hohmann, who has some very good suggestions. I urge all to read it and will buttress his ideas with a few suggestions that I read elsewhere. First, your sign, in addition to saying "No Trespassing", should also say "No Soliciting". Or these can be two separate signs. At any rate, they should be prominent, plainly visible.
If at all possible, don't open your door. If at all possible, open a nearby window (or one on the second floor of your home). Do NOT engage them in conversation or that can be construed as welcoming them to your property. Simply point out what your signs say, reminding them that they are trespassing and that you will call the police if they don't immediately depart. End the conversation right then and there. If they don't leave, then call the police. Remember that bluffing is a sin against honesty. Be polite but firm, and remain in control of any interaction, keeping it brief. Do not divulge or confirm any personal information whatsoever.
Do not let your emotions overrule your intellect. It's quite possible that these people have friends in the background, just waiting to film a temper-tantrum on you part. Don't give them that opportunity. Speaking of filming, please record your interactions. Zoom on their faces and any identifying information (such as badges and sleeve insignas). If their cars are nearby, record them with license plates. If any reporters are accompanying them, get them on your recording devices as well.
Along with praying our Rosaries, we must act with courage and resolve. If we don't use our God-given civil rights, we will lose them. I will post more news and ideas as I learn of them.