Covering Painted and Wallpapered Walls

[SFBadger]

My wife and I are preparing to paint our hallway, and need some help. We have 3 layers over the original plaster - a layer of wallpaper, then paint, then another layer of wallpaper. The outside layer of wallpaper comes off easily, but the paint and first layer of wallpaper needed to be chipped off inch by inch on the section we did last weekend (about 10% of the enitre area). We don't have the stomach to do this for the entire hallway, so we are wondering if there is a short cut. We do not want to replace the plaster with drywall.

We have taken off the outer layer of wallpaper, cleaned the painted surface of old glue, and the paint/wallpaper that is left is very strongly adhered to the plaster, no loose spots. However, the paint is textured/bumpy, and we would like a smooth surface for painting.

My question is, can we just fill the rough surface of the existing paint surface, then sand and paint? If so, what should we use to fill, joint compund, or something else? How should the wall be prepped before filling/sanding - should the paint be sanded first?

Would it be possible to get a plasterer to add a skim coat over the paint? Any other ideas, or should I just suck it up and spend the rest of the year chipping? (If it matters, we probably won't be in this house in 3 years)

Thanks,
Dan