Hi Jeremy,
I thought the same thing and did it with 1 power and 1 USB lead.
USB Lead:
It pays to use the best quality USB lead you can get and use a 5 mtr lead instead of joining 2 together.
Depending on your USB gear get a Powered 4 port hub to suit eg: USB2 or USB3. I use the smallest powered one that I can find. They are sometimes hit or miss but sometimes the cheaper ones outlast the more expensive.
They can suffer over time from the weather getting in so I replace the hub once per year. They are cheap.
Into the hub I plug a Canon 450D (has its own power), QHY5 Camera, Moonlite focus controller (has its own power) and my dew heater's USB connection for stats (has its own power).
I have a Meade 10" SCT and it fits at the back of the tube.
Power lead:
I use a regulated 12V, 5.5 amp plug pack which connects to a power box I made.
Inside the power box are 4 DC to DC adjustable regulators (cheap $1 ebay), with fuses. As well as direct 12v connections. This is also on the back of the scope tube.
I dial in 8v for the Canon, 5v for a laser, 5v for hub, 12v for the focus controller and 12v for the dew heater.
Some power supplies are better than others and you may want to separate power for the dew heater. I have done this and it's only another thin figure 8 wire tethered to the other 2 or use 4 core wire for power to power box and dew heater.
It's a real treat to only have those 2 cables. Good USB management at the scope end is critical I have found and once it's all working nice, test it before last minute setups.
I have found that when using USB hubs in this manner, it helps to always use the same USB ports on the PC. It's like if you get it wrong once, it keeps haunting you.
Cheers,
Damien.