Storage Advice For Hard Drive Setup

Hi everyone. Avid reader, first time poster.

So I'm looking to reduce the amount of heat my PC puts out and I figured one way to do so would be to not have my 5 hard drives going all the time. So I've been looking at ways to change this setup and I'm posting here to seek some advice from those more knowledgeable.

So I have 5 HDDs, 1 OS, 2 I use sometimes and 2 I seldom but occasionally access. For now I'm looking at options for the 2 I seldom use.

The options I've considered are either putting in a hot swap bay to swap the drives in as needed, something I'd like to read into. Is this a viable option and does anyone have experience with this?

Alternatively I was considering buying an external caddie for one or both the drives, though the issue for me there is only have 1 eSata port or USB2 and I'd hate for it to becoming considerably slower to copy files.

So if anyone has any advice or recommendations or have attempted a similar goal, I'd appreciate any responses.

Cheers.