How to handle Gmail with limited SSD space

I'm taking the plunge from a MacBook Pro with 500GB storage to a new MacBook Air with only 256GB storage. This scares me because of so many items that can quickly clog up a hard drive.

I'm concerned because the Library/Mail folder on my MBP currently has 26GB of mail in it (even though Gmail is showing only 3GB of my storage used online). I absolutely don't want this to happen on the MBA. If I change the option under "Keep copies of mail for offline viewing" to something like "All messages, but no attachments" or "Don't save any messages," should I expect to see this number be much lower.

A recent Cult of Mac article suggested not using a dedicated email client and use the browser only, but I'd really rather not go that route if at all possible.

Any advice on being leaner and meaner would be greatly appreciated!