Wow, what an interesting AU you've got here... quite the timeline, imagine how differently DBZ would have gone if Gohan and Android Eighteen somehow fell in love. Well, as they say in Rick and Morty, infinite realities. Imagine, Krillin would still be alone, his daughter wouldn't exist, what if everyone found out? Would there be a simpler solution to all this, wow, this would be a clusterfuck, imagine, they try to destroy Android eigthteen(not that they could.) and Gohan attacks them. I'm sure Gohan would obliterate Cell way before he caused any real trouble, my mind reels with possibilities. But it would mostly be a clusterfuck.
I like the idea to add Bulma at least consider adding her in the story to.
I like Gohan/Bulma mix. :P
It would be nice to get some story with adult context that has more deeper story telling. the only other one i seen like that was Reprogrammed and is a very good story i would not mind to get one more like that.
the author know how to write a lot of details so it would be interesting to see how would he do with given option.
The chapter 1 look interesting even if it's just about Gohan and 18 first encounter and it was all about XXX you could use it for making alink between then at least at first purely sexually and use the given base to make more deeper story and bond between them it would make pretty good story in my opinion.(i will assume that you will continue to make more of the current story with the base story offered to validation)
The given base story i give it 9/10 - it is clear that it was a rushed and made fast for base plot but given that in consideration i set for mark 9.
I like the way of thinking in that sugestion it has good possible connection with fist chapter.