Or if someone hits you from behind. You will get ticketed. You could get ticketed just for having it stick out that far. A real bed extender, a set of those magnetic lights made for towing dead vehicles or old travel trailers and saving your the head aches and possible costs is worth a few extra bucks.

What do you fellas with short truck beds do to support you yak? I've got 7' with tailgate leaving 5' of yak hanging out the back. I was thinking about ripping a 2x4 and making my own extender. I'm guessing if I get T style extender out to about the 9' mark I should be fine.

You can buy THESE... I just don't feel like spending $60+ on it.

A red flag only covers you out to 4' of overage. Anything past that you can, not necessarily will, get pulled over for.

(Texas Transportation Code 621.206)

A vehicle or combination of vehicles may not carry a load that extends more than three feet beyond its front or, except as permitted by other law, more than four feet beyond its rear.
Subsection (a) above does not apply to vehicles collecting garbage, rubbish, refuse, or recyclable materials which are equipped with front-end loading attachments and containers provided that the vehicle is actively engaged in the collection of garbage, rubbish, refuse, or recyclable materials.

If you have more than 4 feet of overhang and want to get technical and be perfectly legal, you'll need lights and/or reflectors at night and, at a minimum, a red flag for daytime. If you can secure the yak without a bed extender, there is no need to waste your money. The amount of overhang is from the rear of your vehicle, not the extender. I use a red flag only night and day and have not had any issues. If you want complete peace of mind, get some lights.