The Leviton z-wave dimmer has a default setting which is changeable via the driver. Check this post.
Now, I don't own one, I own one of the plug in lamp modules and hate it because I can't find any LED bulbs that don't make it whine like crazy. But I have been told frequently that I could hear a mouse fart in the next county so I am super-sensitive to those types of noises. In general, they get good remarks here on the forum but are less widely used for some reason.
This function is also available in the GE Z-wave Motion Switch. Even if you don't use the motion part, you can set the default level via the driver in HE. Also, this would allow you to use the motion when in day or evening mode but not in sleep mode (so as to not upset the wife).
Inovelli devices also have this feature but you (and I) missed the 10 second window when they had stock available in the last 3 years, so that's not really a viable option unless you can find one on ebay.
Others might have other suggestions for dimmers with a default level setting. But that the term you want to look for "default level".
Another option would be to use a button controller like a Lutron Caseta Pico and smartbulbs. This allows you 100% control over the bulbs since you are not controlling them directly. However, this does not allow you local backup if the hub goes down. I only use smartbulbs where i have a manual backup method (for example, in a lamp. You can turn the lamp off and then on to force the bulbs to come on if the hub goes down. Depending on your risk tolerance and your lighting fixtures in your bathroom, this might be a viable option as well.
