Many thanks for that thoughtful analysis, Red 
Brexit (+ 0 UKIP) = 29 seats
LD+Green + SNP+PC+SF+Alliance =^ 29^
Re the objection to counting all Green or SNP votes as Remain:
This is why a PV is the only way to determine purely the Brexit / Remain preference - so you'll be supporting a PV then !
All the established parties - especially CON & LAB - will have a hard core of voters who will vote tribally, even if they disagree on major policy issues
I regard a PV as the risky option of last resort, if the HoC / govt won't do their jobs, but it would at least tell us what the electorate choose now
- but this time any Leave option must be a specific one, whether No Deal or WA
The 2016 ref asked a very general question, which encompassed all imaginable ways of Brexiting;
now we know the only available options for achieving Brexit, it would be fair to ask if either is still preferred to Remain