Re: Pickup recommendations - clean rhythm guitar
I think everyone has overlooked the most obvious choice; the Seth Lover set. They are magical in a semi hollow. They can have a nice bright jangly clean tone or you can soften it up by rolling down the tone knob. The neck is smooth and clear. The A2 magnets keep them from ever being too bright or having too much bite. Since they are un-potted, they have a breathy top end that shimmers and offers incredible note bloom. If I were looking for the best clean tones from a semi hollow guitar, the Seth Lover would be choice without hesitation.
If the OP wants a bit softer tone with more rounded edges and a smooth note bloom with slightly warmer overtones, the Antiquity set would be wonderful as well. For what the OP has asked for, in my opinion, these are my recommendations of all the Seymour Duncan offerings.
Good luck and let us know what you ultimately do (Seth Lover).
Jeff
Edit.... it looks like Jeremy mentioned the Seth just above. I want to give credit where credit is due.