Oh, OP, I am so sorry !!!
I am extremely smell sensitive and also too 'uptight' in every sense of the word (can't easily use the bathroom if I know ANYONE will be going in after I will, can hear me, etc.,.). My husband's parents, sister, and he all take forever in the bathroom and have no compunction about noise, smells, or specifying exactly what they're going to do when they're going in the bathroom. I swear I used to make myself sick thinking about all this when I was much younger!
For a long time I wouldn't even talk about it, just seethed, and then I finally explained my discomfort to him. He has ZERO sense of smell and obviously no 'bathroom issues' so he had to learn to understand where on earth I was coming from...I'm a repressed Southerner, him, not so much

.
Anyway, we've fortunately gotten to a place where we each (DH, DC, and I) have 'our own bathroom' and a guest bathroom -- 30 years later -- AND when we're traveling for vacation and DH needs to relieve himself, he will often go to a different bathroom in the hotel.
But it did take a long time and a lot of resource building (so to speak). In your current situation, I'd just explain it's untenable in the mornings and that he can either get up early, use the bathroom for its one DESIGNED purpose (baths and toileting and handwashing/teeth brushing) and/or use another space to read, recharge and relax (DD's bedroom for heaven's sake if that's what it takes and he needs that kind of time just to surf the net and read.
Good luck!