I normally move seats before trips to ensure I can trim with gear. I don't like carrying extra weight.
When the kids were younger it was sometimes difficult to get enough gear and kids forward. We sometimes hung a pair of gallon water jugs across the bow the canoe, dangling on either side, in front of the carry handle. I don't have any pictures. It's about as far forward as you can get the weight.
I prefer to kneel. My solo doesn't have a fixed seat, so there's no trouble adjusting trim. I paddled a tandem with no seats for a while, that worked great in rivers with real white water. I could slide back to make sure the nose didn't plunge over drops, then slide forward to trim flat in the pools.