I don't know what you mean by a "short" 90
They do make street med 90's, med 90's, Closet 90's
4x3 closet 90 street, for a 4" flange.
Any of these will work for a toilet, adding the 45 is ok too.
I'm using a 4x3 closet bend close coupled (with a 1" stub of 3" pipe) into the short 90 elbow, laying on its side, into a 45 street el, also laying on its side, into a 12" horizontal run of pipe that ties into the wye on the stack. Can I use that short 90 elbow in the horizontal position in a toilet drain line? Is the 45 OK on its side? It's all PVC if that matters.