The recall is probably for the steering. If you stil have the y-type steering that was OE it is not part of the recall. If you upgraded to the t-type for the 08.5+ then you may qualify for new parts. Nobody seems sure whne they changed the steering to not allow installing it wrong and breaking tie rods so bets to have it checked if possible. Good luck on getting parts as it sounds like they are in short supply and individual dealers can only do so many per month.
Bio is usable if it is prepper correctly and kept clean. It just has a lot better chnace of contamination from water and the refining process has to pull enouhg of the crud out of to stop any kind of deposits. You can probably safely do B50 mix but a lot depends on the refining and storage of it. In these close toerance CR systems it is a risk and you have to balance that with dino fuel availability.
Diesel performance shop on Maui sounds like a dream career. Not sure you have enough vehicles to support it though, unless people are will to ferry from other islands. LOL! Would probably end up working on gassers to pay the bills.
Are you having any other symptoms like white smoke, excessive grey smoke under hard throttle, long cranking times, hard starting?