Be more creative! There are lots of easy solutions to your non-existent dilemma, and I’ve mentioned them in multiple other (Pace Partner related) threads! And they already exist - without having to create “more pace partners”… One way to up the power ante and ride at a power level between the existing PP categories, is to ride “in the wind”. Ride off the front of the PP peloton (without leaving the drops zone), and you will find your power requirements will be much higher. This requires skill and practice. Another way to obtain a ride experience between, say C.Cadence and B.Brevet would be to select a Time Trial (TT) bike before dropping into the C Category PP peloton. You will be deprived of the draft (but other riders will not be deprived of yours), and you will have to push about 20% (YRMV) higher average power than your same “normal” averages when with Cadence on a regular bike. If this is too much for you at first, then you can even attenuate your power requirement further, to be only slightly higher by selecting a Gravel Bike and using the same mechanism. Riding “in the wind”, using a regular road bike, then a gravel bike, then a TT bike, will give you gradations of power above the standard PP output such that you will be able to “graduate” to the “B” Category pace partner in no time. Obviously, all of these techniques can be applied to achieve a power level between D and C as well, or B to A and even above that. Frankly, I’ve not tried riding a TT bike with Anquetil, but one can hope (and train), right?!
While the term “recovery ride” probably has the widest range of (and often mis-used) definitions than any other level of training, depending on the Zone model (3, 5, 7, 9 zones???) to which you subscribe. But it doesn’t really matter, as long as you know which specific target heart rate or power level or nominal blood lactate level falls within your own definition of “recovery”, you can easily place yourself in your own “recovery” zone using one of these techniques. The “gaps” between the Pace Partner are not that large when using these tools. At the other end of the spectrum, you can push to VO2 levels within your own Cadence PP by merely falling back from the peloton until the proximity animation warns you of being dropped, and then pushing VO2max power until you reach the proximity animation warning at the front (or as long as you can last!) Rinse. Repeat. Now you’ve got HIIT intervals with a PP too! Easy-peasy.