You don't mention what your shock cord material is, but perhaps there is space to be gained in how you are bundling that up. Take a look at this for a possible idea on how to minimize that bulk...
https://www.rocketryforum.com/threa...-shock-cord-entanglement.179146/#post-2414357
When I had a model under initial construction and started looking at available 'real estate' in the payload bay, I ended up purchasing a longer length of airframe for the payload section (I built an Av-bay without an external switch band, so that increased the length of coupler expending into the payload bay,
and used a different nose cone with a shoulder at least an inch longer than the one supplied with the kit, more effective space lost...). I'm sure since the Ariel is already built, that is not a 'quick fix' option for you.