Hello and welcome ! :)
I have no direct experience of the Black Dogs - and have never put my Mules in anything other than my Les Paul, but I think the Black Dogs sound like your best bet , based on three things:
1) When I enjoyed my Mississipi Queens in a Basswood 335 copy ( For clean(ish) Blues tones ) - but raised the question as to what B.K.P. humbucker would give a similar richer, thicker tone ; one of the guys on here said he thought the Black Dog would be pleasing ( in my case ) - and I quote it in your case, as at least one assumes they may be a feasable tonal choice for you too, that is to say, they are not thought to be incompatible with a semi-hollow.
2) If you are coil splitting them anyway, I feel that the thicker and more powerful Black Dogs would better survive the process of being split - and still sound confident, whilst still 'Old School'. when you need them to. The Mules are great, but their authentically 50s 'P.A.F'. sound is already quite open, before applying the the coil split.
3) I put a Warpig Neck pickup in a fully Hollow ES-175 copy ( for clean / Low volume Jazz tones )- and I could still tell it was a hollow body. Even the very powerful Warpig, still had the characteristic B.K.P. subtlety and adjustability.
I hope the Black Dog owners can comment further. :)
P.S.
In a semi-hollow, I tend to feel that a more powerful magnet / pickup makes the Bass strings sound 'tighter' for Funky stuff - and riffs in general.