Pretty specific question on track separation along a curve

Hello!

TL;DR:
Planning layout. Era 5 British outline. Peco code 55. 180 degree curved parallel track. Outer radius 40cm. Inner radius 37.35cm. Fixed 2.65 track separation throughout that curve. Mocked it up. Mark 1 coaches clear each other by approx 2-3mm.

Q1: Is that 2-3mm separation sufficient for reliable operation going forward, or is it asking for trouble?

Q2: For era 5, is there anything more "overhangy" than a Mark 1 and would it mean trouble on that setup?

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Rejoining the hobby after the odd decade away, and I’ve read several encyclopedias worth of posts on the “safe” minimum distance to have between curved parallel tracks, and while the consensus seems to be that separation should increase slightly on curves to allow for stock overhang, I’ve also read that if you mock it up and it works, you should be good to go, and that the potential problems are less likely on larger radii, and that it all depends on the stock you’ll run, as well as on the type of track.

All of this leaves me guessing a little too much… So I think I’m really after input from those who may have a similar set up to me or have been through this already:

I’m designing my first layout in n with Peco code 55 track. I’ve mocked up the parallel curves I want with flex track on a radius of 40cm or 15.74in (outer) and 37.35cm or 14.7in (inner), maintaining the distance of Peco’s 6 foot way gauge throughout, so (feeling brave) I’ve not increased the separation at all. It’s a single 180 degree double track curve. I’m modelling Era 5 (only British outline), so I think my longest stock will be Mark 1 coaches. (Some Mark 2s maybe?)

With the setup I’ve just described, those Mark 1 coaches just about clear each other by around 2 or 3 mm.

I’m very tempted to go with that margin and start laying track, but I don’t know if in operation it will be reliable or whether that is just too close.

Also, being quite new to modelling Era 5, I’m not entirely sure if stock longer or wider than the Mark 1 coaches exists, because if it does, I don’t want to preclude myself from being able to use it on my layout in the future. (I don’t own any Mark 2s - would they cause a problem with that 2.65 separation?)

So, to summarise, is that distance on those curves safe enough to proceed with? Or should I add a few extra mm? I just don’t have the experience actually running layouts to be able to answer that question, nor do I know if Era 5 stock exists that will overhang even further.

Lastly, might be worth adding that having it “prototypical” is secondary to the space I have available. I like the way the current separation looks, and it would make much better use of the space I have available.

Thank you!