I'm fortunate that in my own OEM HID upgrade to my everyday vehicle (Nissan Altima) that its OEM HID system uses Osram D2R capsules...these are actually manufactured from the get-go to be used in an OEM
properly designed HID reflector housing. Yes, these exist. Acura, Lexus, Infiniti, Mercedes-Benz, and a few other manufacturers went this route for a number of years. An OEM HID
reflector is actually 100% designed to allow use of a D2R HID capsule. Most OEM's switched to projectors (with the compatible D2S HID capsules) around the mid-2000's, as it is easier to style a vehicle's front end around a headlight with a smaller "frontal area footprint". I think the last manufacturer to use D2R HID capsules in an
OEM designed-from-scratch-for-HID reflector housing was Subaru (2016 Impreza).
In short, no leveling apparatus required for D2R, and there are mounting lugs already in place in my Nissan for the ballasts. My Altima's HID housings' high beams sockets had 9005 bulbs, but they support the superb 9011 HIR1 halogen bulbs with no tab modifications required; I think it was designed to use these in the first place. I tested the entire setup in my garage, and the output is amazing in a 100% legal beam pattern. Will never get pulled over for this (and the next time I take apart the front end, I'll be ready to do this job). OEM rocks in this regard.
Just in case anybody is thinking about it, you can't use a re-based D2R capsule from an eBay plug-and-play kit in a reflector housing originally built for halogen use. The lighting result will completely fail for the same reasons eBay plug-and-play re-based D2S kits fail, fail, fail when used in halogen projectors.
So, to help answer the question: if you do remove the Odyssey's halogen headlamps, and install the Honda OEM HID headlamps and hardware, but the installation of the leveling system is just too overwhelming, you may be out of luck for HID.
Luckily, we have people like
parmm on our forum to point us in the right direction. There have been a lot of improvements in halogen bulbs made by manufacturers like Osram, Philips and GE (all suppliers for OEM's) in recent years. The Gen 4 Odys with halogen headlights use H11 bulbs.
See this link for details on an Osram H11 and GE H11 comparison by
evo77 on the HID Planet forums (both are winners). The Osram H11's our own
parmm talks of get good reviews on the Subaru and Toyota forums. Similarly, the guys on TacomaWorld also sing high praises of the GE H11's.
I currently use Philips Xtreme Vision H4 halogen bulbs in our two ancient Odysseys (191,000 and 205,000 miles), and I'm a fan. Our cars (Civic, Accord, Corolla) use the amazing Philips HIR bulbs (9012 low beam, 9011 high beam in only the Accord) with their better output and decent lifespan. I'm a fan of the newer performance halogen bulbs in our small family fleet of older vehicles.
OF