Hey, wolcome. In regard to your question, I would say, that as long as it is his wish personally to have it, it's ok, as it is OK from both your point of view. If he is doing it solely because of your insecurity to get his way unprotected with women (another thing that you should talk about, safe sex should be a must) I doubt that this will work out long time and will never be held against you.
Generally you should work out some kind of common middle ground both of you can agree to, before you start with all of this. No one should have major concernes that he or she keeps sweeping under the rug. It doesn't sound like you already managed to do so, because there are so many uncertainties and worries on your mind still. I certainly know the small town problem, it just came up for us as well, even though in a more theoretical and indirect setting.
Wishing you luck and some peace of mind.
Facts: 30, female, bi, v-type relationship with Sward (husband, straight, mono) and Lin (boyfriend, straight, mono), poly-fi and co-primary.