Is there any disadvantages with my plan?
Yes, you still risk some of your funds. So you can do better.
I will give the steps with Electrum, but Electrum may not work on your Win7 and you
may need something a bit different than I say. However:
1. Install Electrum onto an offline computer. Ideally newer than Win7. That computer will not go online until the transactions are confirmed and arrived to your HW.
2. Import into this offline Electrum the private keys of the addresses you have funds in.
3. Install Electrum onto an online computer.
4. Import into the online Electrum the addresses you have funds in. You'll obtain a watch-only wallet.
5. On the online Electrum create a transaction that sends the funds to the HW.
6. Save the transaction (you cannot sign it yet, no problem), copy it to the offline computer, load it into the offline Electrum, sign it (the offline Electrum can sign, has private keys), save it back.
7. Load the signed transaction into the online Electrum, broadcast it, wait to get confirmed.
You can do this with one address or all. Since you work with cold storage, it's safe. The only weak point is the USB stick you'll use to transfer data, maybe you can do that with camera if both the online and offline computer have it. However, it's safer than your idea of setup.
If Electrum cannot be installed on the offline computer then maybe you get temporarily another computer you can keep offline until the tx is confirmed, or maybe somebody can explain how to do this with Bitcoin Core (I did this with Electrum, I didn't do with Bitcoin Core, I don't know if it's more difficult or the same).