I’ve found a split testing solution that lets me hide a global div element via css… i.e. adding a display: none. The experiment works on all pages of the site.
Convert Experiments: Supported! $139 per month! 15 day free trial.
Optimizley: emailed… waiting to hear back. Probably not included in their basic package.
Experiment.ly : emailed… email bounced… they want me to register now that my email is lost. Ha!
Maxymiser: no prices shown on website… I guess that means expensive.
I also searched for : affordable multivariate testing, and cheap multivariate testing, but no real relevant results.