First - it's not a vacuum actuator, it's low pressure pneumatic.
There are a couple of different ways to "bypass" the actuator, they involve "locking" it engaged, either by forcing it into the engaged position and then welding it engaged, forcing it into engaged position and then putting nylon tywraps to hold it engaged, or replacing the actuator itself with a metal spacer.
All three of these will require manual hubs if you want to be able to disengage the front axle, but the decision as to how & when the hubs should be engaged or disengaged is a personal one, you can get out and engage them everytime you select 4WD, you can leave engage them in anticipation of needing 4WD, or you can leave them engaged all the time, there is no requirement to disengage them.