Your current set works, so if you want to go long hose then just start with getting a 6-7ft hose for the primary and a necklace. I'd assume you have a R195 Octo? If you are happy breathing from it then keep it.
I have the R195 around my neck and am ready to donate my primary in an emergency and switch to it, or my octo if it can be controlled, I am happy to breathe of the R195 at depth, even in the 'pre-dive' venturi setting (assuming flicking that switch will be the last thing on anyone's mind).
With the necklace - and I would not be surprised if the DIR gods frown upon it - I also suggest to clip the octo hose to a hip D-ring (pull release of course) so it does not dangle when you are in horizontal trim (see the attached pic). I like to use the premade silicone necklaces instead of the self-made bungee one's due to comfort, but most are a tad large, meaning that the octo may hang around your sternum and not right up your neck, which is actually more comfortable and easy to grab.