Firstly Jan is not a good time to visit far north queensland if you picture yourself sunning and swimming on the beaches. Stingers, crocs and rain are the constants for that time of year . Whilst it may not rain every day, the humidity is high and many don't like humidity. Cloudy and tropical lows can come or even a cyclone. This goes for Townsville to Whits and just a bit lower.
Rainy season is until about end of March.
With that said, you can visit and there is lots to do, but don't expect blue skies as a given.
Whits- its expensive getting boats around. Anyway the only island you can really visit at the moment is Hamilton as Hayman shut- actually Long island is ok- but your options are limited. I like Hamilton and its back on its feet after the cyclone in March this year. Its not a cheap island though. Airlie is more of the backpacker crowd - but no beach there.
If you have never driven 4wd, don't start on Fraser. It is one of the hardest places to learn on and it will be busy in January with chopped up tracks which usually compounds beginners problems to no end. Driving in sand is a skill. 4wd you hire for Fraser usually are only hired and driven on Fraser. I would be surprised if you can take it beyond to the GC. So my advice there is to get to the island at Hervey Bay and then do some day tours. You will enjoy it far more than stress dealing with digging your car out of the sand if you have no experience.
Townsville and Magnetic Island are enjoyable and a few things to do that way , but no more than a couple of days. 1770 is a nice place to stop as well.
You could focus your trip more on the Sunshine coast and maybe hinterland of the Gold Coast as well if the north has scared you off.
Source : https://www.tripadvisor.com/ShowTopic-g255055-i120-k10951483-Townsville_Whitsundays_Fraser_Island_Gold_Coast-Australia.html