Clicking hotspots in no specific order

Hello All,

I am hoping if someone could help me with an issue I am facing. I have attached my story file as well. On slide 1.1, I have five images with hotspots over them. The navigation is specified in the triggers section. So, clicking first hotspot takes you to slide 1.2, clicking second hotspot takes you to 1.3, and so on.  I am intending to achieve a functionality wherein I can click on any hotspot in no sequential order, but the Next and Previous buttons should appear only when the last hotspot is clicked (doesn't matter if its the first hotspot or fifth). Before that, the user should be able to navigate between hotspot slides only by clicking hotspots and no navigation buttons should be visible. To add to my woes, my client wants custom Next/Prev buttons which you could see in the story file. 

I know this could be done easily if one clicks the hotspots in a sequence but the intent is to click on any hotspots and have the Next/Prev button visible when the user clicks the last hotspot.

Any help would be appreciated. 

-Shiva