Tracking visited slides without a variable for each slide

Hello all,

I have a course that has 45 slides in it.  Some of the slides are gated (they have to complete certain activities before they can click next). 

I also have a custom next/prev buttons.  On the start of the slide - the Next starts off as disabled on the slide start. I have a var named EndOfSlide...when the interactions are done - I set the EndOfSlide to true - I have a trigger on the Next button - when EndOfSlide is true - I change the state from disabled to normal, and the user can click Next to move to the next slide.

The customer has requested to be able to go back to a slide that has already been completed and be able to just click thru without having to wait also have the slide return to the initial state.

I can't just set the slide to resume saved state, b/c when I come back to that slide the interactions are in the state where left. 

Without having to create a Slide_X_Visited (where X is the slide number) variable for every single slide - is there a better way to do this?

Any advice would be welcome.

Thanks

_Rob