Rte 48

[scooke]

8a with all boxes positively ticked across, isnt the negative aspect still to come(8)?o????d?

28a uncertain to say blessed rightly or wrongly with no frontiers(10)?o?d???e?s

16d did men pen nothing to become so tolerant(4-6)o?e?-??n?e?

12a not little green men, scientiest say more like horses of a different colour are they(5)?r???

[TheWinner]

could 8a be downside?

[chelle7272]

28a borderless

[TheWinner]

16d open minded

[chelle7272]

16d open minded - anagram

[donny48]

Do you now have any more letters for 12a ?

[mallyh]

12 prone?

[mallyh]

sorry ignore that x

[donny48]

I struggle to parse this beyond rone/roan, but I frequently find this with Rte 48.

[scorpiojo]

12 Greys?

[donny48]

Or even grays ?

[bhg481]

TW - downside sounds good

[TheWinner]

12a might even be Brown 

[bhg481]

grey is the UK spelling and is known as a type of horse. Brown is just a colour - I'd go for greys (as scorpiojo)

[TheWinner]

yes greys, found this

https://tvtropes.org/pmwiki/pmwiki.php/Main/TheGreys

well done team. . .