If you take disposable poncho’s I would add several feet of duct tape. The wind on the water, in a storm can make a light poncho useless. A bit of duct tape will keep the poncho close to the body and out of your face.

I roll my own. For a round roll I start with paper wrapped around a pencil then wrap as much tape as I want. Once complete just slide the roll off the pencil.

For something flatter I wrap duct tape around a business card (this fits nicely in an Altoids tin).

Good Luck and good fishing.