I sadly can't talk much about BoC as I ALWAYS go Corruption over Crimson simply for the Worm Scarf but since I'm currently doing a Master Mode run and before that didn't get Reaver Shark a lot I can give some tips.
The Underground Desert has a new item called the "Bastet Statue" that increases your defense by a whopping 5! Combine that with Campfires + Heart Lanterns and you become incredibly tanky.
Don't EVER neglect potions. People say fishing has been nerfed simply because of Reaver Shark when it still gives you access to the best potions in the game. Going underground and fishing for Armored Cavefish to make Endurance Potions and combine that with Ironskin. Regeneration and the above set up and proceed to laugh at Master Mode Skeletron's attempts to hurt you.
This is purely theory crafting but the new whip the Snapthorn carried me hard through EoW and it should do well against BoC's first phase as well. Even though it does Summon Damage whips scale of Melee Attack Speed so getting Feral Claws from the Underground Jungle which you'll need to do to get the whip in the first place is well worth the trouble.
Back to fishing. The Falcon Blade is a fantastic Pre-Hardmode sword. Not only does it swing fast but its decent knockback helps keep BoC at bay during its second phase. Slap a Feral Claw on yourself and you should be able to kill it fairly easily. You can obtain it from Iron Crates from fishing.
If you're going a Ranger build don't forget that Fossil Armor is now obtainable much earlier than before and gives different bonuses now increasing Ranged Crit Chance and 20% not to consume ammo. Also 13 Defense is nothing to laugh at early on.
As you said it may be difficult to craft yourself a full set of Gold/Platinum but I personally found it to be very much worth it. The set can carry you from EoC all the way to Skeletron and I personally found it much easier to obtain bars now with what seems to be an increase in chest spawns (not confirmed) from normal gold chests, underground house chests and deadmans chests but also Fairy's telling you where to find chests as well. The bars you get will last you awhile and a bit more. Just make sure to mine the chest out as fairies can't tell if you already looted the chest or not. Only if they are player placed or world-gen.