Watch the VII - V - VI - IV Locrian online guitar lesson by Robbie Calvo from Modal Expose
Improvising over this chord progression is really tough because you never feel like you've resolved, even when you have!
My approach was to find melodic hooks and phrases that worked well as motifs from the G# minor 7(b5) arpeggios and also the E9 arpeggios. I can use the E9 arpeggios because both chords share four of the same tones. G#, B, D, F# to be precise.
I also employed my A major 7 and D major 7 arpeggios to create lines over the E, F# minor 7 and D major 7. Think of these phrases as consonant passing tones that relieve the tension until the G# minor 7(b5) chord comes back around.
Of course some nice scale runs always work well to build a crescendo. Play the Locrian mode starting and ending on any of the chord tones and you'll sound as good as you can given the inherent tension.
I think you are going to have fun playing over this progression. You may even end up waving the white flag in surrender - let me know how you get on!