This is just a suggestion, but maybe, is it possible to add the option of set slider in full screen layout: Yes or no kind of thing, just like when one can do when they click customize on the front page slider. Maybe this could be included in the next update of customizr.
I nearly wrote to Nicolas on this one, because it was such a good idea. Until, that is, I saw that this is included already.
I presume your front slider width is reduced because in Appearance > Customize you unchecked "Full width slider".
As you know, to add a slider to any page, you scroll to the bottom of the page and select "Yes" on the slider button labelled "Add a slider to this post/page". That opens up the panel for you to select the slider etc. There is another slider button in that panel: "Slider Layout : set the slider in full width". Set this to "No" and the slider on this page will be reduced in size exactly like the front page slider.