If you can fit the items you want to put in your sump in a 10 gal
tank then ya it will be fine.
Are you planning on putting your skimmer and heater down there? If so you will also need room for your return pump.
Something else you might want to look at is those clear rubermaid tubs.
Maybe a 20 long vs a 20 high?
I like a large sump simply cause i can put more water into the system that way.