I think yet again we're in danger of generalising, and of preaching short-term experience as fact.
The best answer to these sort of things is "do the detailed research, and then experiment". You'll get lots of people telling you that you'll never do any good with it, but just look as the situation with beef cattle feeding at the moment:
After 60 years of trying to analyse and define everything that a cow needs to convert food to muscle, and trying to devise handling and housing systems to cut down on labour costs, people have finally realised that self-service silage and kale is the best and easiest way to keep cattle though the winter. Outdoors too! I've suggested this to local beef hobby farmers, and I get moans about field poaching and what-not.... well... that's because you're overstocked!
I dont question the pressures modern commercial farmers are under from the supermarkets (and it is the supermarkets, not the consumers), but smallholders are not in that game - nor should they be.
If you want to develop a system for your pigs to feed natural, local, produce, then I applaude you. It won't be easy, but you should certainly try, and let us know the results! I will be doing the same sort of thing when our pigs arrive, and am quite content to have years of trial and error getting the fat/meat/health balance correct.
The general retort to this sort of stuff (so I've found) is "oh, but what about animal welfare!!!"... *sigh*, you would hope that all smallholders have animal welfare at the forefront, but that doesn't mean we need to pretend to be commercial farmers, and copy their systems.
