Jeff, first I would use your "normal" exposure for the shadow values. Regardless of the SBR in your scene, you will still need to hold shadow detail to keep a strong image. Next are the high values. Since you are using FP4 which deals well with the large contrast range, I would just give it a try. Efke 100 would also be a similar good choice, as it deals with extreme contrast well. (I used Efke 100 in the following shot)
The next thing I will suggest might be a bit more difficult for you, but please give it a bit of consideration. Rodinal is a great developer, but in this situation I would switch to Pyrocat-hd. The advantage here is in the highest values. It will hold detail for you when the rodinal starts to lose out, due to the burnt edges of the cholla. The final ingredient here will be the type of development used.
Had this exact situation to deal with a year or two ago. I was shooting into the sun in a water canyon where the sun had just crested a ridge line. Use a lens shade to keep the sun off of the lens as much as possible (if even possible) and reduce the flare as best you can during the exposure. Meter the shadows and the high values (shadows will likely be about ev 10 or 11, high values at 18). Expose several sheets and record the informaion about the light you have (oh by the way, use box speed, keep reading!). I did a "normal" development at first, based on my typical numbers and came up with a very thin sheet of film. It had the high values well enough, but the bottom was just too thin at the extremely reduced development I had used.
Started thinking about stand development and decided, what the heck, I have nothing to lose at this point. I knew I had enough exposure but was concerned with the high values running off the charts, so I did a 1:1:150 development with pyrocat for about 45 minutes (I think that was where I ended up). Did a full minute of agitation at 70f (4x5 ABS plastic film tube), set it aside for 20 minutes, did another 10 seconds and pulled the sheet at 45 minutes. I was stunned with the results.
Had a fully developed sheet of film with shadows fully developed and high values which would print nicely. The developer will run out of steam on the high values fairly rapidly due to exposure, while the bottom end continues to creep along slowly. It may take a couple of tries to get the right development balance, but shoot several sheets to get your times down properly. This is a must-use for these shots, as far as I'm concerned. I just don't know of any other way you can get a fully developed sheet of film without jumping through too many hoops during exposure. The compensating effect from this type of slow development, edge effects, sharpness, shadow contrast and tonality must be seen to be appreciated. Initial agitation must be uniform or development artifacts will be the result.
So, to answer your question, yes! Just expose for the shadows and develop for the highlights. Best, tim curry, tucson, az.