I may be able to help here as I have flown Wilga's with and without slats. With that amount of power the added drag of slats will not be noticable IMO. The Wilga lands very slowly without slats & uncannily slowly with them. There is a slat (inverted) on the tailplane if memory serves me correctly, and the wing slat extends across the top of the windscreen. The model I flew with slats appeared to have an unmodified wing with the slats just added on.
Regards,

John