While I don't claim to know a fullproof way to get that crisp bite-thru skin, I have in my last 3 batches (I take my meats in cycles... finally came back to chicken after 3 years of beef and pork) achieved what I would consider contest worthy thighs. Now I may be stating what everyone already knows, but just encase this is not the case... there are two rules I have come to accept as truths regarding yardbird BBQ tactics.
1. Low and slow is no way to go.
2. Technically, BBQ is meat "that is "cooked by the direct action of dry heat resulting from the burning of hard wood or the hot coals". (as per USDA Code of Federal Regulations, Title 9, Chapter III, Part 319, Subpart C, Section 319.80 found online at http://edocket.access.gpo.gov/cfr_2011/janqtr/pdf/9cfr319.80.pdf gives you the specifics of what BBQ is supposed to be in the governments eyes... though I thought it said specifically indirect heat (it doesn't)
The crisp skin can only be obtained by rendering the fat sufficiently from it as to let the skin dry or crisp. This will not happen at 225. My thighs get cooked at 350 - 375 for no less than a combined time of 50 minutes, and usually come off the grill at 190-195 degrees, and have crisp skin. Do I use butter, no... but you can. Some even use Margarine as it has a higher heat tolerance than butter. I don't use that either. The reason I don't is that I want my spices to stay on. Applying or basting anything after the spices have been applied to my chicken has not boded well in results for me. I do cook with indirect heat, but will flip the thigh skin down the last 5 minutes or so and relocate the thigh to a hotter area of the smoker... say closer to the firebox or above a gap in a tuning plate or the likes.
caution... Skin is flamable... keep that in mind. Patience is key. I plan to do a 24 pack or so of thighs this Saturday.
Perhaps I will take pics if I don't botch them. 
So with that being said... How do I (we, actually... being part of a team) do our chicken?
Ok. A few disclaimers.
This isn't the only way, so don't treat it as such.
Good Swine Almighty isn't a Championship Team (yet), you won't find us on TFN takin on Johnny Trigg or that arrogant @$$ from Georgia... Whatever his name is.
We are two (big) guys who know good BBQ, love to eat good BBQ, and got tired of gettin kicked out of all you can eat rib places that serve crappy ribs... It just wasn't worth the effort anymore.
Crispy, bite-thru Chicken Skin...
The brine I am sharing here works best with a salty rub of your choice, like salt and vinegar potato chips. I have one that I put together personally but will not share the recipe. If you PM me, I might consider mailing you some (no charge). Gotta leave some things a mystery.
For 8 average sized chicken thighs (skin on):
2 cups apple cider vinegar
1 cup EVOO (I have heard that this can be substituted with veggie oil or even peanut oil, never tried it)
1 egg, 2 if small
1 heaping tablespoon of salt
1 teaspoon of poultry seasoning (pre-mixed thyme, sage, marjoram, rosemary, black pepper, and nutmeg)
Beat the egg lightly in the vinegar and oil, add seasonings, mix. Personally I use a large zip-lok to let the thighs marinate in. Make sure to get the seasonings in the tighs as well as can for marinating in the bag. If possible, turn and shake every 30 minutes or so. Leave to marinate no less than 1 hour. I usually leave it for 1 hour, start the fire, then put them on when I'm at temperature (350 - 375)... 2 to 2.5 hours total marinating time. I have let it go as long as a day... too much if you ask me though.
Thighs go on in a moderate to cooler part of the smoker if there is such a thing on your setup. When you put them on, they are set skin up and skin covering as much of each piece as possible. I suggest putting your dry seasoning on now, top and bottom. The oil and egg from the marinade will help it stick. As with other smoking experiences... Consistency is key. Put them on, shut the lid, don't open it unless you need to, maintain temp. Make sure you are smokin when you put them on if you want smoke. At 350 - 375 you got about 50 minutes of smoke to absorb. Plenty to impact the flavor, just don't waste it.
About 40 minutes into it, have your temperature probe in hand (9 times out of 10 you're well over 160 at this point) and check your temps. Note the state of the skin, it should be starting to crisp. Time to move the thighs to the higher temp part of your smoker (or go to 400) and turn them skin down facing the heat.
Now... I can't tell what setup you have. So some common sense will have to be used. Most oils are flammable as is chicken skin. Too high of a heat, or being too close to a heat source will surly send your chicken to the flaming gates of hell in a heartbeat with little to no warning. Also, the oil in the marinade is still on your chicken. Keep this in mind. Better to prolong the skin down exposure at a lower temp (350 - 375) and not go up in flames than to take the burn baby burn approach. wait until the skin crisps. normally no more than 10 minutes for a total of 50 minutes on the smoker.
Serve it hot off the grill... hot. no wrapping, no setting, no foil, just come and get it while its hot.
There you have it... all but my dry seasoning for the chicken.
...Its the clencher...you win.... 
