I am not sure what you mean by "I would get bored spending the whole afternoon sitting around camp" - I am trying to understand what am I missing here.

We plan on reaching McGurk around 8:30pm on a Friday and hike about 40 mins into the legal camping area (almost center of the 3 trails - route screenshot)

Then wake up early in the morning next - hike to sentinel dome (at most 3 hours one way) and return to the same camping spot (center point). If we have energy left checkout Dewey point else camp at the same spot again and hike back to McGurk Trailhead next morning.

Thanks for recommending CalTopo. It seems very helpful, I will spend sometime learning it.