Most Helpful Guy
Just have an open discussion with him. It doesn't have to be in the bedroom, but maybe ask him his opinion of it and if he's ever wanted to try it. I'm sure that will reciprocate a responding question to you and your thoughts on the subject.
Wanting to experiment in the bedroom isn't terrible at all, and he may be turned on by the idea you're willing to go beyond what you have been doing.
Anyway, just be calm and in a comfortable setting, but also keep an open mind and respect his thoughts, too.