I've been playing around with an interesting new setup where I honestly can't remember where I first saw it, but made me realise that I was not doing something really obvious, and you know... it might just work.
That little thing was offsetting the cap recharge of my Raven battleship by using Capacitor Power Relays (the one that reduces the boost amount to provide a large capacitor recharge) to allow me to permanently run my shield booster.
I was obviously a bit perturbed about reducing the effectiveness of my main form of damage mitigation (my XL shield booster further reinforced by a shield boost amplifier) but by taking a 20% approx cut in shield booster effectiveness I could run the booster permanently, thereby allowing a much more resiliant overall setup (I previously used capacitor booster charges to offset the capacitor drain for high damage missions where I needed to run the booster a lot, which meant that a lot of my cargo hold was dedicated to cap booster charges, and even then I only had about 20 minutes of sustained shield boosting, this is usually enough to see the mission through, but the price soon began to mount up at around 3,000 isk per cap booster charge.)
First tests were a bit disapponinting, I arranged for a corpmate to come along and go full fire on me, with a Navy Raven of their own, 7 missiles going against my weakest resist (EM, which even though I was using invulnerability fields, were only providing around 48% resist) stripped my shield bare in about 1 and a half minutes. Definately resigned this to the 'not for PVP' school of thought - add in the possible ways that capacitor can be drained in PVP and the very delicate balance of regen vs cap use is skewed in the wrong direction.
However, this setup absolutely shines in a few level 4 missions I have tried - I never dipped below 95% shields at all during the 2 missions I have had a go with - 'Massive Attack' vs Serpentis (using racial shield hardeners) and 'Silence the Informant' using a generic hardener setup.
I did have to go out and invest in a Caldari Navy Shield Boost Amplifier which greatly improved my shield boost rate to offset the reduction from the Cap Power Relays, but that was 'only' 77 million, which should be possible to make back in less than 5 missions, and saved me the equivalent of 15 days training to be able to use the advanced tech 2 shield boost amp which I was sorely lacking in my setup.
The Caldari Navy Raven has been a significant investment, but it has been well worth it to date, with luck this stalwart of battle will serve me well in the future.