どうせだから seems to occur more when some sort of causality is in place or some sort of explanation is expected, and it also often appears as a standalone sentence. And I guess どうせだったら would be more likely to appear as a statement of condition. But the line seems blurry, considering both are similarly defined as "might as well", so I wonder if they are interchangeable in some sentences.
Can どうせだから be used here? What about どうせなら?