The first part that stands out to me is when you remark that "no medical history other than inguinal hernia operations around about the time when this neurological issue started". It would be important to know if he had any of this pain before this surgery. It is not uncommon for a nerve to be "nicked" during a procedure like this and the pain could stem or at least be contributed to by that. This information may or may not change how you would treat him, but to me the order of events is important.
From the description of the pain it sounds more like sciatic nerve pain, but the way to distinguish this is to look at the exact flow of the area of pain (dermatome charts can be helpful here). I doubt this would baffle neurologists, but the pain can come about without significant back problems so I suppose it could be overlooked. Either way, burning pain is neuropathy. The importance of knowing the path of the pain is that it will help you to see what discs/areas the nerves involved originate from.
The points you are using generally seem appropriate, so what I can offer is only what I would do if this were my patient. For issues of this nature we tend to focus on huatuo needling and tuina. Personally I use very little electro-acupuncture, relying instead on tuina as it more directly effects the structural issues (my bias). I would caution you, however, that electro-acupuncture can aggravate neuropathy cases as can direct needling so you need to experiment and watch the patient response (both immediately and symptoms wise) closely.
As we don't know whether it is a "brain" problem, or a "structural" problem or simply a nicked nerve from the surgery you have to branch out the treatment a little. I would just stick with what you are doing for at least 3-6 treatments and only alter it significantly if you are not getting results. Personally I would change around most of the upper points (UB 12, UB 14, etc.) and incorporate the following:
GV 20 - motor cortex
GB 20 - release the neck
Huatuo of C1 (communication from brain - tuina only), T1 (any bone problem), T7 (circulation into the lower abdomen and lower legs), L1 (adrenal, testes, inguinal hernia hx), L2 (kidney, seminal vessicle, inguinal hernia hx), L3 (prostate and leg circulation), L5 (colon and leg circulation, sciatic pain) and/or the eight liao. Without seeing the patient, I would focus on T7, L1, L2, and L3. Adding or switching to L5 or the eight liao based on the path of pain.
All of the other GB points are fine, I would add UB 40 which does a good job of releasing the lower back muscles and improving circulation in the leg and consider SI 3 and UB 62 instead of UB 60 and LV 8 instead of SP 6 which effects the circulation the knee and leg better.
We usually start and end each treatment with strong tuina on the neck and huatuo areas. I would focus the tuina on C1, T7, L1, L2, L3 and L5 looking for any deviations in the musculature surrounding the spine. Cupping may be appropriate in those areas as well.