I'm trying to only export articles of clothing as FBX files but I can't find an option for that. Also, if I try to drag clothes into the canvas area without a character selected, it won't allow it. Is there any work around for these issues?

Objects attached to character (cloth/accessories) cannot be exported as FBX, or added to the stage without character itself.
You'd need to convert those items to a Prop first.
Convert an item of clothing to an Accessory first and then detach from character. Then you'd be able to export it to FBX.

I used this in UE4 for having modular outfits you can use the hide mesh tool to hide every part of the mesh except 1 poly. You need at least one poly for it to export correctly. You can change the texture of the skin to be invisible for the one poly or you can export it FBX to a third party and delete the body mesh poly. But in general you can do this easily for swapble clothing in game engines.