I think it is no longer controversial to assert that Trump is a pathological liar in the clinical sense, for the reasons you assert.  
I think an important instance is the lie Trump insisted that Donald Jr. tell regarding the now infamous meeting with Russians during the campaign.  Jr., Jared and their lawyers had agreed that their best bet was to pull the proverbial band-aid -- that is, to tell the truth quickly and candidly, knowing that it would hurt, but also knowing that if they didn't tell the truth, it would hurt more if/when the truth eventually emerged. This is sound strategy legally and as crisis management. But Trump Sr. was having none of it. He insisted that Jr., Jared and their attorneys lie about the meeting: who attended, what they discussed, etc. Then he sent his own team of liars -- Sanders, Sekulow, et alia out to perpetuate the lies; and of course they all got caught. Yesterday, Sanders, in another pathetic performance, tried to continue spinning the lies.