I did it when I was in my 20s a few times and I hated it. Tasted suspiciously like vomit.
However I did not give up there. The grown up spider/icecream soda involves tonic water, french vanilla icecream, crushed strawberries and a dash of gin, imo.
What can I say, I was young and it feels like it should work so I kept thinking maybe the champagne wasn't good enough, maybe it works better with dry instead of sweet, etc.
If you hate tonic, maybe substitute one of those fancy Fever Tree club sodas then?
To be honest, the whole thing doesn't sound that appetising to me! I'm just not a big spider fan in general, so swapping the tonic probably wouldn't help.