I’d recommend staying in Epernay which is the centre of Champagne country and a lovely town. About 3 hours from the tunnel.
We did the same run in the opposite direction last year but did Como to Epernay in one hit. We went into Switzerland, over the Gotthard Pass and then into France. Depending on time you could explore some of the Alpine passes. The down side is that you need a (expensive) vignette for the Swiss motorways.
