Doors and Windows - skylight rough openning forgiveness?

Looking for folks that have installed a skylight to enlighten me on the forgiveness of the rough openning size. To clarify I have a rough openning on width of 22 1/4 between rafters. Length is not an issue. I would like to install a Velux skylight that the specs call for a rough openning of 22 7/16 width. I'm falling 3/16 short. I have installed many windows and the rough openning in window installations is very forgiving as you can move the window 3/16 with no problem and shim more or less on the opposite side. Question before I spend the money is if I can do the same with a skylight. Velux gives the outside dimension of the skylight but not the inner dimmension. Does anyone know what the true size is of what they list as a 22 square skylight or at least let me know if there is enough wiggle room to make the installation work? I have contacted them by the way but as of yet they have not responded.

On 24" center rafters, you should have 22 1/2" between them. The RO of 22 7/16 will fit in a standard opening. You may find moving the skylight over one rafter will fit, if that would work for you. Otherwise, you may not have enough space. Contact the manufacturer to see if there is any wiggle room.