The tune I know for The Lakes of Ponchartrain is not the same tune as that normally used for The Homes of Donegal - the latter is the same as Tramps & Hawkers. You could swap the tunes though, as they would fit the lyrics in each case.

But I realise there are probably lots of variations on all these songs and tunes anyway.

Ewan MacColl also used the Tramps & Hawkers tune for a song in the Radio Ballad "Song of a Road" about the building of the M1 motorway (a major highway in the UK). I don't recall the song's title, but it was about a mother singing to her son about his father being away working on the road. See this thread for the lyrics etc.