Therm calibration
Nice looking bird! Spatchcock is the only way I cook birds now. I would highly suggest you get a calibratable dome thermometer and a grate temp thermometer, measure the grate temp @350 then adjust the done therm to match it. Dome temps don't cook food, grate temps do. Even though my vault door therm passed the boil test, it read 50 deg. higher than the grate temp measurements I was getting from the guru. So I just adjusted it now they both read the same. I cook @350 also and 4.5-5 lb birds take usually 1hr 10 min @350 grate temp annd skin is good. 400 makes the best chicken skin imo. a little trick i learned a while back, if you want crispy skin, pat the chicken skin dry and put it in the fridge over night again till the cook. that will dry it out a little. Good luck on future cooks.