Obviously with all the different dialects of Romani people are going to favour slightly different uses of phrases in different parts of the world for different circumstances. Latcho- means a journey and Drom-means road. I have heard that Romani in other parts of europe use the phrase Latcho drom to basically wish some one a safe journey but I have not heard it used in the UK or Ireland where the Romani generally would say Dza Develsar-God go with you, or something similar.
Of course Irish Travellers don't speak Romani they speak Cant or Gammon but there hase been influence both ways in terms of adopted phrases and words especially in the wake of government policy to lump the Irish Travellers and Romani together on offical sites regardless of the wishes of either side.
So it does seem possible that Irish Travellers might have adopted a derivitive of Latcho to mean a Travelling man of whatever description? But again all the Irish Travellers I know use Pavee in relation to themselves.
Clear as mud now eh!!!