I think the trees can be as tall as you'd like, but they'll start to look pretty different from Earth trees.
I spent quite some time developing a world that sounds a lot like what you're working with and have since then taken chunks of that setting and made it more extreme for roleplaying game environments. Here's some of the stuff I did before I added any magic:
The trees are all interconnected. At multiple layers. The branches in each layer of the canopy grow into each other and allow forces to be distributed throughout the whole biomass. This shifts wind from being something that might blow the trees over to something which requires much needed ventilation to lower layers. The trees, flora and fauna will grow to optimize this (See also: How termite mounds work.) Think of it almost more like designing a reef than a forest. The trees get big as a team and build their own ecosystem.
The trees eat rocks. This one of the ways you can get around the compression and tensile strength of wood. Have it self-petrify. If you're feeling especially serious about it have it grow literal veins of iron throughout and make it natural rebar-reinforced concrete. You could also play with and optimize the grain structure. The root structure is designed to distribute weight at "ground-level" and to penetrate whatever bedrock the forest is growing over. The roots don't primarily absorb water any more, they're there for heavy minerals and structure.
The trees get nutrients and water the whole way up.
-Lower levels are designed to trap falling debris and form ponds and small lakes with the last of the water that's managed to make it this far down. Roots grow into these to acidify them and break down any biologicals that filter down into usable nutrients for the trees. This layer is its own ecosystem, with fish analogues and very little light. The forest floor is effectively an acid-oozing desert with very little life.
-Lower-mid levels are very structural, dropping their leaves and extra branches to facilitate air movement and gas exchange. Depending on the size of the forest and length of day, temperature changes due to shifting sunlight could generate a fair amount of internal wind, which would make this area inhabited by flora and fauna able to hang directly from the branches and get their nutrients from the air (Things like Spanish Moss.) Sections of the tree could have lighter or darker leaves, or flip-able leaves light on one side and dark on the other to facilitate this process.
-Upper mid levels are where most of the leaves are. Branches grow more thickly here, full of leaves which trap rain and provide nutrients to the tree and the vast amount of flora and fauna living on this layer. Most of the light gets blocked by this layer, so if you want to have any "normal" Earth surface life you'd probably want to adapt it to live here. Due to the amount of biomass here this layer is where what we would consider soil is deposited. Something like 85% of the water works its way through this layer to be redirected and absorbed by the supporting branch networks. From here build a rain forest with understory and canopy levels stacking in such a way to keep permitting dappled light through.
-Upper levels are where the clouds are. The leaves here are for redirecting and taking in water. They are clear and are used for generating alcohols, not sugars. This keeps them from freezing and they sweat the alcohols to lower the leaf temp and encourage condensation. The forest makes its own rain when it needs to. You can get around a lot of the fluid dynamics issues (or at least trade them for different ones...) this way.
This is my first answer, I hope I did everything right and it helps give you some ideas. Thanks for building what sounds like a really cool world!