Which of these non-ideal options for bath/shower waste to new internal stack in compact bathroom

[Lull]

We are fitting a (very compact) new bathroom upstairs as part of an eco upgrade/retrofit of a victorian terrace & have two non-ideal options of how to connect the 40mm bath/shower waste to the new internal soil stack we are fitting. We are running it horizontally along under the toilet waste to avoid cutting/damaging original floorboards.

 

We can connect to the back of the boss connection as in the first option shown in photos (not really accessible in the future), or bring it out of the boxed in wall to connect onto a more accessible boss connector on the ‘front’ of the stack - it will project with a ‘triangle’ from the wall slightly but hopefully this can be disguised enough with skirting etc to not look too messy. The stack will all be boxed into a thick wall, but can have an access panel. There will be a 110mm rodding eye above this section on the soil stack & the sink waste will enter it higher up.

 

I recognise this is far from perfect with the bends and vertical prior to entering the stack, but needs must to avoid damaging the old floorboards under the bath to run it between the joists. There will be an accessible trap underneath the omnitub bath to help reduce risk of blockages.

 

However, which is the preferred/more sensible option out of these? I considered a manifold boss to drop into, but that wouldn’t fit unfortunately.