I like to use 0.5% Phenonip. I am generally a fan of Liquid Germall Plus, but this is not suitable for non-water applications. (Please refer to the post on preservatives for more information.) Optiphen might be an option for you (I've never used it), but Tinosan is right out for the conditioner or shaving bar because it doesn't play well with cationics.
Also, please allow your bars to cure for a day or two. I usually do, but I found myself without a conditioner bar and used one a few hours after making it. It melted away in the shower, so I only had about 50% of the time I'd normally have with a conditioner bar.
So sorry to have left this information out!
But as I like to think of everything in life as a opportunity to learn and grow, I encourage you, my wonderful readers, to share your feedback with me. Let me know if I've messed up, let me know if a recipe worked or didn't work for you, and let me know what you think!
And this is a lesson for me - I tend to print out my recipe, then write the updates in grease pencil on the plastic sheet in my binder. When I've been copying out recipes for this blog, I've tended to use the version on my computer, instead of including my notes. So guess what I'm doing today - updating the binder!