I've fished waters where bait boats were the number one method of getting end tackle in the water, including under trees.
At Taverham Mills while I was bailiffing it, there was a bay on the island that from a particular swim people would frequently use a bait boat to put a bait under the overhanging trees.
I had to go out a few times in a dinghy to recover and rescue bait boats from under the trees. Carp rarely visited the spot, it was absolutely foul stinking silt. While fishing that swim I'd found that out by watching the area, casting and dragging my marker float back, boat journeys and wading confirmed it.
Most anglers using a bait boat do the same thing. Rig and bait in hopper, send out to feature, nice pile of bait around the hook.
Without a bait boat, you may think of alternative options, that 2 bait stringer, a spod or 3, a bag or mesh. That bag or mesh can also be used to give a clean drop through the willows...
Don't forget, I did used to use a bait boat, but my ethics probably bit back.
This sonar searching may give you some idea, but sonar only tells you weed, not what type. Eelgrass has holes or clear patches, that will not necessarily show up with a bait boat and sonar. Then some other weed like the dreaded blanket weed may show up clear, or as a fuzzy layer, but a layer on the lakebed may make your hookbait disappear.