Glide64 worked with the binary version. Now it also works with the version Gentoo compiled for me. I copied the configuration from them binary version... don't know which setting actually caused the error message described earlier. Anyway, Glide64 works now, thanks.
First the good stuff: With Glide64, the sun's showing up the way it should :bouncy:, and there seem to be no weird polygons blocking the view when using the bow. So that's very good.
Now the bad stuff: Glide64 seems to have problems elsewhere. There are disappearing roads and stuff (see screenshot), the GUI map looks weird, and in general, it looks more pixelish than glN64. It's hard to catch in a screenshot, don't know if you can see the difference (look at sky in the first shot or the floor and walls in the second shot). Both Glide64 and glN64 use 2xSAI, I also tried Bilinear and Point filtering with Glide64.
Also, Glide64 freezes extremely often (image gets stuck while sound continues playing). glN64 had that at first too until I fiddled a bit with the settings... maybe something similar will work for Glide64 as well, I don't know.
I'll use glN64 now for everyday use, and switch to Glide64 when I have to use the bow a lot

Thanks for helping me out so far.