Re: Ulf Stricker here!
I think there are also different approaches to this topic.
One could be: Pick an ostinato with your feet and try to read a magazine or book while playing that ostinato, completely forgetting what you are actually doing. Do that for like half an hour and try to stay focused on the content of the magazine. So the ostinato becomes something you never will have to think about any more.
A second way could be a practicing routine like the following:
Figure out the microtime of your ostinato, i.e. 16th, triplets or whatever. Play the microtime along with your hands. Try to play various accents while keeping the microtime hand to hand. Change the stickings and try to keep the ostinato. Play any rudiment you can imagine over the ostinato.
Try to establish a second timeline in addition to the ostinato. For example: If the ostinato is a cycle of 12 notes, try to play a cycle of 5 or 7 with your hands, then switch it to just one hand, leaving one limb open for soloing.
Or give your third limb (besides the feet) a fixed task. Example: Play left foot clave, a Songo Bassdrum and a cascara in the right hand. Add all imaginable types of accents with your left hand.
Try to split up not only within hand and feet. Example: Play a double stroke between your left hand and your left foot and try to solo against it with the right part of the body.
There is a lot more to discover. Your only limit is your imagination.
I´m sure you will come up with own ideas soon!