Yeah, I mean, I'm used to the inventory management at this point, but the ideal scenario would probably be to have a button that switches where you want to transfer it to/from. So you press Y/Triangle and then maybe LB/RB (disable the sections swapping while a slot is selected) to swap between sources/destinations. This should solve being able to easily transfer from/to the freighter, vehicles or the containers as well, but that's a whole other point.
I think at some point they'll have to revamp the inventory system because they keep adding new cargo sources and it's all getting a bit out of hand.
BTW, regarding farming and making good money, I followed this procedure but planted double the Fungal Mould. Chasing around for cacti can be a bit tiresome at times but I'm also doing missions and messing around in the galaxy in general, and every half an hour or so I make 10 Liquid Explosives and get 10 mil. I'm not really playing optimally or anything but I'm at about 75 million credits right now which is more than I've ever had in this game. The prices for ships and freighters are still pretty high but I'd be content to be able to buy one of those new exotic ships (as a second ship) so I guess I'll keep grinding a bit while I do missions etc.