Yes I would plan for an entire day if your heading up north, Willow Beach is MM52 so your looking at least an hour if hauling, would take me almost 2 cruising. Hoover Dam is another 1/2 hour +- winding through the canyon, pretty cool stuff there and you might get to see some big horns if your lucky. Willow has a store and fuel but no restaurant. The river is cold 52-53 degrees year round, so if your planning on swimming up there be prepared. My kids didn't mind swimming in the chilly water, but I could get only so deep... Also watch the river above Willow, seen/heard of many torn up props, absolutely doable, just be careful.
If you plan on heading up north check the weather, that lake can get nasty if the south winds get howling, I've had to tuck up in coves waiting it out. 30+ miles of busting waves wouldn't be a fun day.
I don't know your plans or how many are in your group, but if possible scout a good beach/cove with the Wellcraft, mark your territory (tents, chairs, big scarry dog, etc) and then go back to retrieve the houseboat.
I've only taken out a house boat once, but was surprised by their rule of not allowing private boats back by the house boats and no towing other boats until the house boat was well out of the marina. We had to adjust our plan of how to get my boat out of the marina along with the house boat, sure glad my dad was along for the trip as my wife would have had a fit trying to drive my boat or the house boat.