Something which I foolishly omitted in my earlier post...
With Rodinal and APX100 I (and the rest of the world, obviously) found that agitation and temperature (with time compensation, use the Ilford graph) could play a part in altering contrast too. So you could consider your agitation, and go to two inversions in place of one for example. Increasing temperature by a degree and compensating the time could also help do the job.
Rodinal is a very adjustable developer and this can be handy for very harsh-contrast sunlight when I've used it down to 17,5C. Equally (and as a slight warning for Googlers), this is also why it is not an ideal beginner's developer of course as, assuming they would want repeatable results, a newcomer might struggle with consistency.