I would highly recommend considering using an Amateur Radio portable. Specifically the Yaesu FT270. Generally 16-20hrs of battery life in continuous use at higher volumes, which is a couple days at trackside. It's significantly better in environments with a lot of interference than a general consumer scanner, and is nearly commercial grade. It's built to IPX7 standards, so it's fine in heavy rain and can take one hell of a beating. Ask me how I know...lol. And it really is pretty much the standard amongst buffs.
It's also comparably priced to any scanner at anywhere from $125-$150, so you get a better radio for the same money. And it's not as hard to program as many like to complain about. That's what the manual is for. It does have an SMA antenna connector, so you would need an adapter for SMA to BNC, but that's a couple bucks.
And since it's a common question, you do not need a license to own it for receive only (unless you live in Kentucky or New York...their scanner/receiver laws are a little overkill).