As a UIM (ultimate iron man without the ability to bank) things are really tricky due to limited spacing, even in OSRS there are storage loopholes for UIM such as Zulrah storage or Vorkath, maybe more i'm forgetting.
There is too much content to be able to fit in the inventory and still be able to do other things. Examples.) Energy Fragments, Stardust, Blood money, Inability to drop a pet that can't be exchanged for points,green bananas. aswell as just items for various fighting styles, I'm sure i'm forgetting about alot more and i do know there is a looting bag for 1k slayer points (which i assume drops on death in the wildy). That is a bit of a grind and I have yet to get it. Even then though those items will still be there to take up valuable space, but even then the risk to have to enter the wildy to insert items is great.
All i'm suggesting is some type of storage for those stackable items that have no inherent value while they are in that form, or maybe even some bank spaces like Deadman Mode on OSRS (maybe like 6?) You don't understand the pain if you have not played UIM, I do know what I signed up for and if nothing is changed i'll understand. I'm nearly maxed, I challenge you to try and see.
Edit: Completely forgot about skilling tools and outfits like the agility/runecrafting/woodcutting. thats alot of spaces aswell..
