Great idea with the Tomcat LV. My kids have really enjoyed paddling the LV over the years and they also used WW kayak paddles, mainly because that's what I had on hand.
That said, a few things to consider:
1. Weight: try to keep the paddle weight down, some of the cheaper paddles are quite heavy and can lead to fatigue more quickly.
2. Offset: my kids all preferred low offset of the blades, between 0-30 degrees.
3. Length: The LV isn't as wide as most IKs, so don't get a super long "touring" paddle unless it will only be used on the lake. The paddle at REI is 200cm and I wouldn't go any longer. If she struggles to use that on the river you can always go with a shorter one. My kids used paddles that were between 185cm - 197cm. In the attached picture my son is using a 185cm paddle that is unfortunately no longer made.