Our daughter and son-in-law live in Goodyear - we visit there frequently. Just another opinion, but Lake Pleasant is a pretty small lake, 10 square miles... compared to Yellowstone Lake (136 sq. mi), Lake Powell (254 sq. mi.), or Lake Havasu (30 sq. mi.). Not that it wouldn't be a good respite from the frozen northland; but, that is a long ways to go for a small(ish) lake. It is also a pretty good commute from Lake Pleasant to Goodyear... although the new (almost completed) Loop 303 will get you there a lot faster than I-17 down to the 101, and onto I-10. About 44 miles, average 54 minute commute (according to MapQuest). Two hours out of each day there. (Probably nothing after the drive from the northland to the desert.) We have made the ride on our scoots from Goodyear to the lake from time to time, just to see some water around there.
Average temps there in January are: High 65º, Low 42º. (Yes, I read that you are from that area, just putting out some averages for planning sake.) Even though it will likely be chilly at night, you won't have to break a hole in the ice to put the boat in. 8)
Not sure about a week-long pass for the park/lake, but I think it is $10 each day for a daily pass.
I get the need for some boat-time in the middle of winter, but that is a long ol' haul for a relatively short time on a small lake. Another consideration: fly down, stay in Goodyear, spend some time with the folks, rent a boat for an afternoon at Lake Pleasant. Yeah, it won't be the same as having your own boat there. You'll have to be living right to make it from the northland to central AZ without running into some real winter weather and driving conditions along the way... and the potential to lose some travel days due to Mother Nature.
We avoid I-40 in the winter, and have run into snowy conditions on I-10 from November through January from time to time.
Good luck with the plans!