My crazy solution for a business/charity - for myself, not suggesting other people would want to do this:
1. Catch the rats in humane traps (somehow - might be very difficult).
2. Keep them in a very, very large cage (females and males separated so they don't reproduce). After being caught, make sure there is no further human contact except providing them food and fresh water and cleaning their cage (don't know how yet - maybe make a tunnel to get them out and when their cage is empty, clean it?).
I understand that they will still suffer and be distressed, especially initially. But this is the lesser evil. It ensures the rats will be safe, warm and well-fed without being able to reproduce. Until they naturally die of old age, they only live for 2-3 years anyway. Human is protected against catching diseases with protective clothing and masks.
Am I crazy? Is this too impractical to ever work? Am I insane for essentially wanting to create a safe rat farm for wild rats and mice?
Rats and mice are a big problem in London and my neighbour currently has big rats in her house that she wants to get rid of...
I am really passionate about rats and mice - even wild ones and I don't want them to suffer.
The main method of pest control for rats and mice is poison. My neighbour told me what happens to mice and rats when they've been poisoned: they immediately seek water and start bloating up, it is incredibly painful and distressing for them, they run around and then stop and he said, 'you wait when they stop until you hear a splat and that means their organs have exploded'. He has absolutely no guilt for doing this and thinks it's great
The current best humane solutions would be to repel them with peppermint oil and sealing cracks in your home, etc but repelling them is just guaranteeing they'll leave into other houses who will kill them.
And as vegans, I trust that you understand just because you don't directly kill an animal, it doesn't mean you're guilt-free in still contributing to the animals death and suffering (no one else understands or cares).
Catching them and setting them free in a park is a similar problem although there's the added problem of putting them in other rats' territories and compelling them to die of starvation etc. Also might be heavily fined for being caught doing this.