Shared blockchain cache files (view-only and spend-key wallets)

Is it possible to copy the blockchain cache data from a view-only wallet to its spend wallet (on another machine)?

Setup

I use two wallets:

a hot wallet, and
a cold wallet

The hot wallet lives on my daily driver computer, and it only has enough XMR in it to cover daily transactions.

The cold wallet has the majority of my coins, and it lives on a hardened machine. It has Internet, but I only ever use this dedicated machine for crypto transactions. It basically just runs electrum and feather.

I only open my cold wallet a few times per year, whenever the hot wallet needs a top-up.

Problem

This process works great for electrum, which only needs a few minutes (at most) to sync.

This process isn’t great for monero. I have to sit for hours waiting for feather to sync. And I’m physically tied to the computer with a BusKill cable.

Solution

What I want to do is reduce the feather wallet’s sync time by first doing the sync in the reduced-security environment with the view-only wallet and then just copy those cache files from my daily driver computer (with the view-only key) to my hardened crypto system (with its spend keys). I’m aware of the animated QR code option for airgapped systems, but that’s not something I’m trying to do.

Questions

I have two questions:

What are the security implications? If my daily machine is compromised, then an adversary could modify the blockchain cache files. What’s the worst someone could do to my spend-key machine if I copy-over malicious blockchain cache files? Is it anything worse than preventing me from spending coins that I have in my wallet?
Is there a guide anywhere showing how I can copy these blockchain cache files from one machine (with a view-only key) to another machine (with the spend key)?