stranger anxiety

Question
Wondering if you can direct me.  I have a 2 yr old beagle/weimeraner (we think) cross (from a rescue group) I got as a 9 week old puppy.  Tonka's doggy Mom did not enforce any manners, and when I got him he was dominant.  My family and myself and my other dog did some tuning with the tricks I have learned of taking the Alpha position, and all seemed to be fine.  
I put an underground fence in, and both dogs loved it as they had almost a 1/4 acre to play on, along with daily walks/runs in the ravine.  This is when problems seemed to start.  Tonka realized that if he barked (that annoying beagle howl) at people/cars/ leaves and chased them along the fence line they went away.  I did not realize this was leading to anxiety when they did not go away, or came onto the property.  Tonka is now a nut bar when anyone (more male)comes near him (even on leash).  Someone coming to the door sends him running with tail between his legs, shaking, howling and urinating everywhere. On leash, I ignore the behavior to allow him to know I am alpha, but what he has started doing is running at people as they walk away and barking up their backsides, almost a "see I made you leave".  
I have strangers bring/give treats as we talk, but more often then not he is so freaked out that he will not take it (a beagle not taking a treat!!!).
Tonka has been on 2 different anti-anxiety meds without effect, even stoned he gets freaked out.
Tonka is smart, easily trained, knows a repertoire of tricks, and can do some agility stuff.
I have done a fair amount of research in dog training, but I am lost and would love any help, I hope this would be an easy fix.
I am afraid this anxiety is going to go to fear biting, and I have a number of children in and out of the house so I am afraid of taking any chances.
Thanks in advance
Tracey and Tonka

Answer
I think the best way to deal with this is to find a trainer that can come to your house,so he/she can see Tonka's problems in the home,and also go through the steps of showing you what to do

So you can call all of the trainers in your area and see if they offer this,or can refer you to a trainer that does,as well as asking your vet-as the best way to deal with this is to have a trainer see the dog and work with you