I would suggest saying pretty much exactly what you wrote in your original post. It makes it clear what your issues are with his actions while highlighting how much you care about him and appreciate his support. I would think he probably has no idea that his actions are having this effect on you. I wouldn't tip toe around the issue or pacify him to try and let him down gently, he isn't a child. His feelings aren't likely to be hurt if you explain it to him like you did here which I personally think was very clear on what you want but that you value his encouragement also. Then have a conversation about boundaries as they can be vague when doing this type of business from home so you both know where you stand with each other.
I think every man is different, and a lot depends on your relationship, but I'm someone who calls it as it is, doesn't mean I am abrupt, callous or don't take his feelings into consideration, but I'm not one to BS and be passive either. My husband is respectful of my honesty just like I am of his. Nowhere is it written that we have to agree or conform and we are clear on those expectations.