Most if not all the sites will likely take 2 or 3 tents, might be tight. All that to say I've never had an issue and usually trip with 4 tents.
There is a really, and I mean really great site almost all the way down Stratton on the left called "The Flinstsone" site as it has large flagstone benches surrounding a great firepit. That one usually goes quick and the challenge is that if you pass up a spot on the way down, and find Flintsone occupied, you have to backtrack ......
Keep in mind that not all the sites on the lake are for paddlers. Some are designated for hikers only. On one trip I was told at the gate that all sites for paddlers were booked, including mine. I arrived late on a Friday to find no free campsites. After inquiring with folks on the occupied sites It became clear that a hiking party had occupied a paddle site. Not hard to figure out as they did not have a canoe

. They reluctantly vacated after some words.
Enjoy the lake/falls. The food hanging cables they provide are awesome. When I was last there the raccoons were particularly troublesome. I have a picture of about 5 raccoons swarming my barrel, hanging from the suspension cables. The bastards chewed by barrel harness.
$61.00 seems normal.
MikeD.