I've been happily smashing through with dual bazookas on hands, dual songbirds on the shoulders, Big boom 
I did swap one arm out for a Minigun on the spider boss just for maximising the damage when he was stunned, which was easily repeatable, songbirds got him to 80%, remaining bazooka stunned him, minigun him whilst the other weapons reloaded then a big second volley and back off.
Even without the heavy legs If you boost up high you can stay afloat for ages by cycling each arm/shoulder in sequence, firing locks you in the air for a moment which allows some energy to recover to boost back up, don't think I touched the floor in that smelter robot fight.

I did swap one arm out for a Minigun on the spider boss just for maximising the damage when he was stunned, which was easily repeatable, songbirds got him to 80%, remaining bazooka stunned him, minigun him whilst the other weapons reloaded then a big second volley and back off.
Even without the heavy legs If you boost up high you can stay afloat for ages by cycling each arm/shoulder in sequence, firing locks you in the air for a moment which allows some energy to recover to boost back up, don't think I touched the floor in that smelter robot fight.