[mothered]

do you think any of them would work particularly well or are they all the same?

They're all manufactured equally to serve their purpose, so It's up to you to apply them without Imperfections.

I’ve managed to find a phone within the £50-60 price bracket, that weighs exactly the same as the iPhone (gram for gram)

Good to read.

Also, with the second account for this method, would it be ok if I brought it using gift cards? Or should I set up a VCC and use that instead?

They're both much of a muchness.

The most Important thing, Is to have no association to your primary account.

And last thing, should I order them both to a pickup location (e.g. amz locker, corner shop, etc) or just to my neighbours/my house?

The wrong Item must be sent to a different address.

That’s what I mean - could Amazon trace it back to me if someone else brought and reported it?

Who's to say that "someone else" Isn't a social engineer who's attempting to SE the company with the wrong Item received method?

Once your return has been placed back Into stock and then picked, packed, dispatched and sold, It's Impossible to pinpoint that you're at fault.

Btw thanks for all the help, I appreciate it

You're welcome.