Can I assume chicken internal temp rises 5 degrees while resting?
Yes 3C/5F is about right. Chicken is always tricky because you're try to get legs at 72C but breast only at 65C (or even a bit less). Several cooking techniques to achieve that but it's for another post... The thermal mass argument seems to make sense although there is also 'more to do' so I would stick to the general rule of thumb and experiment. Resting is essential (but you already know this) either under foil or in a warm area. If your bird gets a bit too cold, you can flash the cut portions for 2-3 minutes in a hot oven; no need to rest again.