In looking at your pictures, aren't those already studs? Or do they have a hex "head" on them under the bracket that you can't see?
But I would think that two spacers, grinding the bracket to clear the primary tube, and correct length bolts or studs would be the ticket.
It's going to depend on the primary tube though, looking at mine, there is no way I'd fit a spacer at the second bolt (from the front) with that primary tube. If yours is the same way, I'd say you'll have to cut the back leg off of the bracket and use only the front bolt. I've seen that done before with AC compressors in that location, I don't see why it would be any different with your situation. It's going to decrease stability a bit, but I've never heard anyone that's used the forward bolt only say it wasn't enough.