So I've been tinkering with mod installations (and rather unsuccessfully, at that) for a good part of the last week and finally ended up with a working build!
I've played through Baldur's Gate what feels like a century ago and later got stuck in SoA Underdark (and stopped playing computer games altogether, for quite some time). I later tried BGT once or twice before there even was EE, checked all the big mods and was annoyed to no end by CtB Candlekeep chores. I did kinda respect Bonehill, for the effort.
So when picking the mods, I tried to avoid going too innovative. I mostly went after the stuff Cahir and @4udr4n installed, threw in Dungeon-be-gone (I like to start new campaigns a lot) and removed most tactical encounters. To me, it seems that there is some kind of an arms race between making your party much more powerful and beefing up all kinds of enemies. I tried to avoid both. I'll stick with all kinds of restrictions, avoid supercharged weapons and to leave the enemies mostly as weak and dumb as they used to be. Yeah, I can deal with a level 5 (or something) fighter with a +4 axe right at the start of the game by reloading until I manage to charm person him and then send him to clear out the entire gnoll fortress, but I don't really want to. I don't want to just totally stomp everybody, either, but I don't think there's a huge threat that I'll end up doing that, as I'm not really good at games.
I didn't want to flood the game with new NPCs either, because I'm not entirely fed up with the ones Bioware made, yet. I have no idea who is well-written and am indeed open to suggestions. As it is now, I added some more BG1 NPCs to BG2 and (rather randomly) threw in Finch, Gavin, Valerie and Kelsey. I have no idea how well-written they or any others are, and I think I'll add Tyris Flare and Angelo in the next version of the build. If you have any suggestions of whom I really don't want to miss, I'll add them straight away.
I added lots of quest mods and stuck to the ones that looked well-maintained. I prefer ones that tend to seamlessly blend into the core game and the descriptions I read told me that my choice would. I went with NTotSC, DSotSC, Ascalon's, Ascension (minus the beefed up fights), Fading Promises, Sellswords, Alternatives, most of Luna's mods, cowled menace, Twisting with the Rune, any extension of Bioware NPC quests I could find, and a few smaller things. Again, if I'm missing out on greatness, do tell.
I don't tweak my game too much. I'm back for some nostalgia and I don't want to alter the game mechanics beyond recognition. I tried to stick with ADnD rules, mostly and I like certain ease-of-use things, like an early appearance of all kinds of containers and bags of holding. I did install spell revisions because original spells were useless aside from a handful and I did try to install rogue rebalancing and parts of divine remix (the ones that give me a few more kits), but somehow, my new game doesn't offer any of the kits I tried to add. If anybody knows what silly sorting mistake I made, I'd be happy to hear it.
Lastly, some mods refused to install. Unofficial items pack didn't want to work, and neither SOD2BG2, nor S9Soundsets could be installed via PI: EET main component refused to run after it detected S9Soundsets. I guess I should have installed it manually beforehand, or selected BG2EE rather than EET and installed this one component before doing the rest. I'll try it sooner or later. What also surprised me was that even though I picked "Add missing movies" in "BGEE classic movies", it still replaced the BGEE Friendly Arm Inn video with the old BG1 movie.
My Install order file was the following: