[mothered]

I think I will reach out to their customer service and poke around a bit to determine if a signature is always required/if my order will likely have one

You can certainly contact CS, but there's really no need to.

If only a signature Is required, Its verification Is easily rendered Inconclusive.

and if they consider a package to be "delivered" regardless of who signs it

They will.

Whoever signs, Is an authorized recipient which Is no different to when you sign.

or if insurance leaves room for instances where the driver leaves it unattended/fake signs/it is not delivered to the actual customer.

In short, they've covered themselves nicely In their terms, whereby they'll use GPS/tracking to mark the consignment delivered.

After the delivery reaches the correct address, It then becomes your responsibility.

Depending on their answers, I may still attempt an order/SE

I'm very Interested In all events that take place.

If you go through with It, please tag me.

and plan to return it/chargeback upon failure, or I may decide better of it, and look for overpriced, truly unnecessary items elsewhere.
If I attempt an SE with this company, I'll be sure to update here in the future in case anyone seeks to give them a try!

What I like about your SEing, Is the fact that you take the time to thoroughly research every angle prior to executing your attack.

Moreover, your approach Is realistic, and not overthinking the SE nor applying an overkill. 

You're an invaluable resource, and your time has been greatly appreciated!

You're most welcome.

Thanks for your kind words.