Sensibly most people suggest to get an external Drum Machine. I'd quite fancy a Drum Brute Impact myself.
I've got a few small sequencers, DNIPRO DOT and Robaux LL8, both very capable, but I've just gone and got a Arturia Beatstep Pro as its way more user-friendly than the LL8 (though Muting isn't quite as easy) its good for other stuff too. The DOT is good for little fills and the in-between percussion bits that can be made to float along as poly-rhythms etc from the 3 channels that have different step counts giving you interesting variety that you don't always need to control.
Personally I'd use Pam's clocks for other stuff rather than trying to sequence Drums & percussion with it.
Enjoy your spare HP, don't rush to fill every last space, this is not like filling sticker books. Resist the urge to 'complete' your rack, its never complete so just relax.