You have a good chance that the pain responds to ketamine, which has an effect on proprioception. Rather than killing the pain it gradually kills off the entire awareness of having a body (temporarily of course :D )
Generally it is not recommended to meditate lying down, because that promotes passivity and rest, but the lazy kind. The half-lotus position is great to practice but if you have not mastered it yet it can be uncomfortable to maintain, even for people without chronic pain. But on dissociatives like ketamine it is IME often a piece of cake to endure such straining. Just be careful not to injure yourself while numbed.
Read some instructions on the half-lotus, like how to bend your pelvis / hips and back, and get in a position that is like someone is lifting you up from an invisible wire suspended from the base of your neck / head.
Trying with meditation first (let's call the result close enough to a K-hole

) is definitely not a bad idea. It is often less threatening and easier to deal with meditative states than strong drug-induced states, I think that is because meditation is much more natural and it happens a bit more at your own pace and own accord.
You can always try higher doses later, that way you first build experience with gradually increasing doses - which is always the best approach. Diving into the deep end of the dosage range might sound effective, and granted: the stronger the ketamine experience the stronger the loss of typical emotional dimensionality is (you tend to be beyond normal coherent understanding of things, if you forget that you are a person there is not enough awareness to fear anything)... but it is not very good HR to take a massive dose without titrating, and potentially unpredictable. Although again granted: higher doses tend to immobilize you.