Fighting Duke before Golem is a viable strategy. I myself tend to fight the Duke before Golem and Plantera in some cases.
Generally a weapon that is fast and that you can aim well will work well against the Duke. As you've defeated Plantera already, I would also recommend going to the Dungeon to get some weapons there if you haven't yet.
For obtaining truffle worms efficiently, having several rows of long strips of Mushroom grass in the cavern layer will get you truffle worms in a fair amount of time. I generally build long rows of straight mud blocks with mushroom grass and then create a pit below for the truffle worms to drop into. There are more optimal methods than this, but it does the job well enough and can get you roughly 1-3 truffles every 10 mins.
And for Golem, if you manage to defeat Duke Fishron before fighting Golem, the weapons from the Duke will be very good for taking down Golem. Otherwise I'd recommend getting items such as the Terra Blade, Death Sickle, Shadowbeam Staff, Tactical Shotgun, or Paladin's Hammer. Terra Blade can be crafted through Night's Edge and Excalibur enhanced with broken hero swords from the Solar Eclipse. Death Sickle also comes from Solar Eclipse, the other weapons come from enemies in the Hardmode Dungeon which you have access to now.
