I can’t comment on drafts but my main concern would be having two toilets directly in front and associated disturbances of doors opening/closing and pax queuing. I think that far outweighs any tray table or draft issue.

Here is link to thread in this forum which discusses seating queries on all 787s, with some photos. I’m sure somewhere 30A has been covered.
https://www.flyertalk.com/forum/brit...reamliner.html

And as you mentioned seatguru I have to point out Aerolopa for a source of hyper accurate seat plans. Done by a contributor to this forum and indeed they are linked into the thread above.
https://www.aerolopa.com/ba-781