Unfortunately you cannot use the full Banks PowerPack with a 4x4 van. But you can install the "Stinger" exhaust package. It will increase interior noise, but after I installed a curved tip, it became tolerable. Some floor sound deadening really helps too.
All the Banks stuff for the E-series is CARB compliant.
Note: Many F-series cat-back exhausts will also fit with some minor exhaust bracket modifications. The Banks muffler sounds pretty good though, many aftermarket mufflers make the V10 sound like a ricer.
The stinger comes with a K&N filter element, which helps a little at the top end. But I really like the AFE complete intake replacement. It added a noticeable amount of low and midrange torque, allowing me to stay in OD more often when pulling hills with a trailer.
AFE doesn't list that kit on their website. The link is for info only. They say they won't ship to CA, but that particular kit actually is CARB compliant, and comes with a CARB sticker.
For tuning, 5-star has the best stuff for the V10, and will build custom tunes for your use. I have the Diablo Predator, which works but I had to modify the tunes to make it work best for towing.
I also installed the Banks Transcommand. Most aftermarket programmers will allow you increase shift pressures (which keeps the trans cooler), but the Banks TransCommand also causes the Torque Converter to lock up sooner. Due to the weights I haul (22,000 combined typical and ~26,000 on occasion) I still use the programmer to increase shift pressure beyond even what the Transcommand does (yes, you can stack a programmer on top of the Transcommand without issue).