The tunnel does appear to have played a large part in you not enjoying your trip. I was getting to be the same. Since changing to now using the Hull-Rotterdam ferry the trip is much more enjoyable. A steady couple of hours to Hull, overnight ferry with a meal and a couple of drinks, a decent night’s sleep and after a leisurely breakfast ready for off around 09.00. We now go this way whether it’s a bike, pickup truck or motorhome trip. Great duty free onboard now too. When in the pickup or motorhome we tend to stock up a bit on wine and spirits on the homeward journey which the ship’s crew deliver down to the car deck for us. Coming home we disembark and are on the way home around 09.00 and home before lunch.
Our usual journey when using the pickup or motorhome is to Chamonix in the French Alps to visit our son and family. The difference in distance between Rotterdam and Chamonix and Calais and Chamonix is 40 kilometres. Not much.