I make deboned chicken thighs all the time. It's my favorite. I like them crisp and browned outside, very juicy inside.
i debone my own, or if i go to a butcher and there isn't a line of people waiting, have him debone them.
They cook faster flat. Sometimes i remove part of the skin, sometimes all, sometimes none. Usually if roasted in oven, i leave an inch or two of skin.
Turn on your oven to max. (yes, believe me)
the trick is not to let any water near the chicken. so
no high sides to the pan you use (1 inch max). I think that's because high sides make some steam stay around the chicken.
Also the pan has to be large enough to contain them all, flat, with a bit of space 1/4 inch or a cm around them.
Low baking rack in the oven, the lowest. If you can watch them every few minutes, you can even put them on the floor of the oven but i'd lower the heat to about 400F in that case.
Put parchment paper on the pan, a bit of oil. season the chicken however you like
when the oven is HOT, put them in on the lowest rack
roast till the bottom side is browned nicely, and immediately turn over.
for juicy chicken make sure you don;t overcook. AS SOON AS the chicken feels firm, test one thigh at its thickest part, cutting into it and seeing if it's got any pink. If not, remove immediately
ALWAYS crisp, brown, and juicy this way