Demountable harness bar allowed on demountable rear stays?

[DIY-Si]

First off, sorry if this would be better placed in the general Tech area, but I thought here was more suited.

 

As part of building my XI, I am aiming to make it eligible for the sprint series. For my ROPS design, I am using demountable rear stays so the bodywork can be accessed/removed as required. The harness bar that I need to fit will almost certainly need to be on the stays, rather than in the main hoop. But if I weld it to the stays, I'm fairly sure I won't be able to fit all three tubes in place at once.

 

Therefore, is it permissable to have a demountable harness bar attached to demountable rear stays? The stay joints are FIA approved, and I'd be using approved joint types for the harness bar. I've gone through the MSUK Yearbook and spent a good while searching online, but I can't find anything like an answer......