I have cooked bone in pork shoulder many times before and I am about to do it again but I feel the need to experiment slightly... My plan is to cook the pork shoulder in the oven for 8 hours at 100 degrees celcius (212 degrees faranheit) then transfer it to my smoker, where i shall smoke it for another 8 hours between 90-100 degrees celcius (194-212 degrees faranheit).  I'll have internal thermometers etc so i know it will hit the correct temps, i am just wondering if I will end up drying the crap out of it.  I can't give a weight on the pork shoulder as I don't have it yet, it will be the entire shoulder though around 4.5 kg maybe  What do people think, good plan or bad plan?  I will be using a temperature probe, I forgot to mention that there would also be a cider bath in the oven and smoker as well. Can't change the order of the cook as I won't be there for the time it spends in the oven (I would have just gone for smoker straight through if I had). Thanks for your advice, I'll let you know how it goes. 
180C (350F) for 45 minutes should do the trick. Just make sure it is piping hot in the middle before serving. Cover the dish with foil to prevent the crust getting any crustier. You will still want to take it off for the last ten minutes of cooking to crisp it though, as the foil will make it soggy. You can absolutely prepare Cottage Pie to the pre-baking stage and fridge (or freezer) it until the next day. You need to cool it relatively quickly though - hot food shouldn't sit around for more than a couple of hours. Place the dish in cool water (obviously not over the lip of the dish) and change the water a couple of times as the pie warms it, then cover and put in the fridge or freezer. 