Sizing wise I might go for a pot bet here. I generally tend to size things a bit bigger- depends on how much he likes to wear his cape- might just half pot it.
Since its so close as to whether we can profitably bet the river here, I think gameflow & history would decide it for me. If I just intuitively felt like I was ahead and he could call lite, that sort of thing.
As far as sizing if we do choose to bet, I prefer a bigger bet as it makes us look polarised. We are supposed to be polarised here and it gives villain added reason to "wear his cape"