It just happens I'm a divorced mom with a DD 11 and a DS 8! We took our first WDW trip when they were 8 and 4. I worried about the same things. We started with the agreement that we would limit our attractions to those that DS could go on, planning for another trip in the future when he'd be tall enough for everything. That way we would stay together and no one would be jealous or resentful. At 8 y/o, you may find that your DS will be tall enough for almost everything anyway - my DS is now tall enough for all attractions.
As far as the restrooms go, I still insist that DS come into the women's room whenever we're away from home. He sometimes grumbles about wanting to be more grown-up, but I tell him I won't risk anything happening to him - and I say the same to anyone who may comment on DS's being in the room. Interestingly, the only place that has ever had an issue with DS being in the women's room was our local YMCA - and the staff there pointed out a family restroom I could use instead. Luckily, WDW has family restrooms as well if you feel awkward taking him into the regular ones. I'm pretty militant about his safety and do not apologize for others' feelings. I'd rather inconvenience a few strangers than live with the consequences of leaving my child alone.
We had several conversations before our first trip about what to do if separated. I pointed out the CM badges and the kids did great. Thankfully, we never were separated but I do think they would have gone to a CM. We had a fabulous time and I'm looking forward to our next big trip in August! Hope yours goes wonderfully as well!
