I'm not an addon expert, but I ran my hoarding account w/o ESO plus for a long time and thought I'd offer some tips:

- obviously you want to create a bunch of alts to hold stuff. The main tip here is to create Alts you might like to play...different classes, make them look cool, etc. You might invest a lot of time and money in them...a fat Breton with an eye patch and wooden leg named Sir Bluballs might not be great in pvp if you ever want to play him, lol.

- my standard at first was to invest in 100 bag spaces with the merchant. That's $20k gold per alt. It's a bit...but there are at least ten different motifs in the game that sell for $20k+ per chapter...some motif expeditions can easily fund your upgrades. Then every alt should invest the time and $15k gold to upgrade their mount space. If you're a non-plus hoarder, you're going to need it, so you may as well spend two months getting everyone to 60. Depending on how old/large your account is, eight toons w 160 spaces can last you a pretty long time.

- I then assigned my mules specific categories. One alt can handle all enchanting. Another can handle provision and alchemy. One for raw mats, and one for refined. I invest in hirelings on all of them...as long as I'm logging in, might as well get free stuff.

- the goal is to not use the bank for any/much long term storage. Otherwise it'll become gridlocked. Move items over as you play then once a day, or every once in a while, log into your Alts and distribute items appropriately.

- I leveled all of my Alts crafting skills. This is not something to grind...just over time, lol. This enables them to do writs, which is a way to convert clutter low level mats into higher level stuff. To start, an alt can easily begin provision, alchemy and enchanting. These return way more than they cost. Maybe you hate writs, but I'll do brief tips on each.

- provision writ: your alt can buy the recipes from the chef/brewer if you need them. Your main crafter can learn and craft stacks of food for your Alts. Just pick up and turn in each day, bam. Note that these are one of the only sources of lower level purple recipes in the game. By holding an alt at a lower level provision writ, you can fill in any you need...or sell them for a ton of cash.

- alchemy: like provisioning, your main crafter can make the potions. Craft stacks of the six turn in potions then just pick up and turn in each day.

- enchant: the alt doing the writ has to make the glyphs. But potency runes can be bought from enchanter npcs, and the payout is 5x any cost.

- with eight toons, you can hoarder for quite a while before it becomes a problem...so long as you find and use a system that works for you. But stuff will still pile up, so what I did when the account got crammed was I did a one-time ESO plus when I wanted some crowns anyway. My mats all went into a craft bag, and my toons were reset and able to go another six months without plus.