I'm having a hard time envisaging what this might look like and how you might tighten the bolts in side the HSS? However if you are fundamentally talking about a single clip angle either side of the HSS (one to each web), then I'd do exactly what KootK noted in his item 1. If your tables give a similar web thickness for single sided clip angles as the wall thickness of the HSS, then I'd say take 2 x single angle capacity for an appropriate configuration with the same number of bolts. Otherwise just calc it out by hand using the same procedure.
Keep in mind you'd still need to check whatever you were bolting into, for example if its a column flange, your bolts would be quite a bit further apart than say a double clip angle either side of a hot rolled I-section web right next to the column web. I don't see why you couldn't turn the angles inwards though, apart from cutting off access to the column bolting, though you could bolt these before fitting up the HSS maybe. Still don't know how you are doing up the bolts through the HSS webs as no access to the inside of the HSS if hard against a column flange or beam web? Sketch might help if you envisaged a different arrangement to that which I am trying to explain.