My suggestion is Ultimate ironman. It's more of a challenge.
A few things that would needed to be worked out is the lootbag, using notes on bank to unnote items, etc. Like OSRS with a few exceptions such as storing only sets into the bank as the con isn't added or not *just a bonus*
Also the EXP rates could be different as well and drop rates like Hardcore and regular ironman. Maybe a little more harder to level to add even more of a challenge to the game.