There used to be a 64' boat local to here that did Wigan fairly often, but obviously could not share with another 57' boat. We shared Johnson's Hillock with him a few times on our 45'.
You need to ride the tailgate going downhill, and you only get really wet when backing up to allow the gates to open. Waterproofing the engine bay is a good idea, and decent foul weather gear for the steerer is a must - you will get wet coming down many of the L&L locks - you will get much wetter doing Bingley 5 & 3 rises than on Wigan.
We regularly boat the northern canals in company with a 60' boat, and there are no problem locks at that length. Don't forget that if necessary you can use a lock on your own and place the boat diagonally across the lock to gain an extra foot or so.
In short, it's a great trip and you will enjoy it. As long as you keep an eye on cills that will be closer than you are used to you will be fine in the locks.