No doubt, Chiba City's Sakae Cho is a tough nut to crack for us who are not Japanese. 10+ years ago, I was a regular customer at one soapland in Sakae Cho but it's changed hands and I lost track of where the manager and providers went. The new management told me I was not welcome. I'm pretty well established in Chiba City now and honestly I don't do my mongering in my own back yard.
How I found a gaijin friendly place was just by having friendly chit-chats with the touts in the area. I also found some Filapina snack bars where I ended up with my pants around my knees on more than a couple occasions. Also, walk into some of the many sex information shops and ask if they could make a few calls for you or at least point you in the right direction. I think you could probably find a delivery service that would be OK with you. Good luck.