If you are JUST wanting to walk to Karakter from Sunset, you can walk to El Zafiro and cut through there, and then walk straight down the beach to Karakter. Although frankly, from Sunset all the way to Karakter, if I'm going to guess, is probably close to a mile. I'm lazy, so wouldn't want to do it.

Regarding access to BSV, if you head through El Z, you can see BSV from the beach, but that really doesn't allow you to see inside the units, unless you ask someone staying there to view their unit. BSV has a gate, and there is not a guard during the day to open the gate. You could stand there for quite a while and perhaps someone would let you in. A better choice would be to send them an email and set up a specific time to have someone show you a unit.

If it were ME, I would DRIVE there to BSV, after having made an appointment to view the units, leave your car there and walk down to Karakter, if that's what you want to do.