No such plans for now, sorry.
Just to make sure everyone reading this is clear: you don't really need much rum. If it drops to zero, the troops do not die. This was changed years ago.
What most players do when they need rum for upgrades or training:
1. Simply buy it in Smuggler's Den. The 30k and 50k packs are the best value.
2. Do some raiding of similarly distanced havens (so that your troops return home around the same time).
Also, when you have excess rum, put it on Market for double amount of lumber (so it almost never gets bought). You can recall it within 72h and then use it. If you leave it longer than 72h, it'll get recalled the first time you load the game, so you can still spend it if you're quick enough (the negative production will start eating it away).
Personally, my rum production is about -1M/h. No reasonable amount of upgrades to any buildings would get me even close to positive, but the above approaches work very well.
Your biggest problem in this game is apathy.
There have been many major updates in similar plarium games, but plarium obviously hates all pirates.
Food/Rum production and consumption have always been a huge problem in all games and cost a fortune to upgrade, but a couple of simple updates would make a big difference here ... but nobody ever complains so you get nothing. (I tried complaining years ago but got no help)
Dragon Stone - https://prnt.sc/pQiqyI0ClVuI
Relics - https://prnt.sc/8g1e8WWrt8ER
Davy Jones Locker is garbage by comparison - https://prnt.sc/WAz-dUXEOk48