That seems like an entirely reasonable way to do it. That's a rather long run, so the larger wiring is probably advisable. With the 1.5HP lift you will need it as well. Actually, my lift is solar powered.

You might be able to direct bury things but you'll have to trench down lower.

Thanks for the input! I think the lift motor will draw about 10 amps at 230V and 20 amps at 115V. The thing that concerns me most is the wire size and picking the right one, plus trying to get wire inside the house for the light switch.

My best advice for wiring to and on a dock is to hire a licensed electrician. DO NOT allow the dock builders to wire this up.

"I think the lift motor will draw about 10 amps at 230V and 20 amps at 115V."

Depending on the type of motor the starting surge can be significantly higher than the runing current.

!00% higher (double the running current) is not all that uncommon) especially for a motor that must start under load.

If the voltage sags during start up the motor will take longer to start, may not even start, and will run hotter with a shorter life.

You need to identify some typical lifts and determine there starting surge needs, then select the wire size based on that.

You may need to deliver 30 or 40 amps during starting without sagging the voltage more than 3-5%.