The main problem, I think, is that there is no eyewitness accounts of the Resurrection itself. We only have witnesses that Jesus was walking and talking at a time after his reported death. We do not have multiple witnesses discussing the same appearance of Jesus and instead appear to have several different appearances described by different witnesses.
There is an unusual commonality in the confusion his appearance caused in each case. Not just the typical confusion of a dead man walking around but a certain initial lack of recognition or belief that the person walking around is in fact Jesus.
Why would people that know Jesus have difficulty recognising him? The text suggests divine intervention in that their eyes were kept from knowing him or some such. But if we suppose the accounts are real witness accounts of a real event we might conclude that somebody masquerading as Jesus was seen, and managed to persuade witnesses that he was Jesus of Nazerath. I'm sure, if Jesus had gained the local notoriety the stories suggest and could draw a crowd as suggested - that there were unscrupulous conmen who at least considered capitalising on people inclined to follow.
I'm guessing that if police were investigating these reports that's the kind of hypothesis they'd start with, possibly ruling it out as unlikely if the witnesses only reported it during one week but then stopped completely. In the end though, I don't think we have the kind of material that lends itself easily to historical analysis through such things as multiple attestation. At best we can say that the doubt/confusion is an interesting issue, it would be interesting to see if there are any ideas as to why that was mentioned. (I forget which is which, I think in Matthew they mostly praise him with a few doubters, and with John we have a woman that doesn't initially recognize him and finally calls him 'Teacher' or something like that? I think Luke has the supernaturally blinded followers not recognizing him at first. I'm too lazy to check right now even though the links are in the OP).
Do you suppose this is good reason to think that people who reported seeing Jesus did not at first 'recognize' him? Perhaps even support the notion that they at least saw something?
As I said, I think it tells us at least that there was doubt about early reports of his resurrection.
Our sources are slim indeed; but we use the same number of sources for drawing other conclusions which are probably not far off, for example, the issues Ehrman points out (from OP).
I don't think the evidence regarding the resurrection is as good as the evidence for Jesus teaching the coming of the kingdom of God. But that's probably because of Q.
We'd almost think such popularity might make it less likely that folk wouldn't recognize him wherever he went—especially men who had previously spent nearly every second of their lives with him!
Notoriety and recognizability were not the same thing necessarily 2,000 years ago. We have no multiply attested witnessing that anyone that knew Jesus well saw him post resurrection.
So, might it be that the sightings of 'Jesus' really took place?
The Criterion of dissimilarity only gets us to conclude that Jesus was executed, I think. Given he died - it is naturally in support of Christianity that a resurrection occurred. In this case we might say that sightings occurred, but this tells us as much about the post-death activities of the King of the Jews as the sightings of Elvis tell us about the King of Rock n Roll.
If you have access to any NT Wright's work - I think he's probably the best source of pro-resurrection history (at least I've seen his name cited relatively often), do you have any idea how he supports the notion?