The two retired men reckon they will have run up more than 3,400km by the time they return from Poznan and Gdansk to their homes in the village of Mountcharles, Co Donegal.
Michael, 61, retired early from his job as an environmental health officer because he is battling throat cancer. Joe, a retired court clerk, is 63.
They picked up a pair of brothers, Aidan and John Doherty, who are in their mid-50s, on their way through Donegal town after filling up at a diesel station outside Mountcharles.
They aim to be in the Hook of Holland by Saturday morning for the 1,000km road trip to Poznan, and reckon they will arrived in plenty of time for Sunday evening’s match with Croatia.
They have never driven a campervan across the continent before.
The four Finn Harps fans, who often play golf together, opted to travel in Michael’s campervan instead of flying “for a sense of adventure”.
Their return ferry fares between Ireland and Britain, and Britain and Holland will cost them €330 each, including the shared cost of the campervan on the ships.
The anticipated €300 diesel total will cost them a further €75 each.
They already have their match tickets.
Michael said: “For about €400 each we will travel to all Ireland’s first-round matches and have our own accommodation.
“We won’t be spending much on food either. We have stocked the van with big steaks and the best prize-winning sausages from McGettigans in Donegal town.
“We have already worked out the next trip for the campervan. It’s taking us to the Irish Open golf at Portrush on Jun 28.
“Mind you, Joe and I are free agents. If Ireland qualify for the later stages it’s possible we might take the campervan on to Kiev in Ukraine and the other two lads can fly back home if they have to return to work.”