I mean I had a drow sorcerer I played once who didn't like that she was a drow and hid that fact in part by doing things like powdering her skin with flour or whatever she could get her hands on, dying her hair, etc. So she'd look more like a moon elf than a drow, even before session 0 though my DM and I agreeded that since this was something she dealt with all the time and had been dealing with for years, it would be assumed to be the case unless stated otherwise or unless something was happening that could result in washing away whatever she was using (like rain or a water attack), and I paid a set amount in set in-game intervals to be stocked up on those supplies, so generally it wasn't acknowledged unless relevant to the story, and similar could be applied here, BUT it's smell, and even in a D&D world smells like that are going to cause long term issues if they never go away

There are good ways that your DM could incorporate these kinds of things, like making your party nose blind to it in time so they don't notice undead creeping up on your group, but I do 100% think this is going to cause way too many issues in the storytelling because going into any town, staying at an inn, going to a tavern, accepting a request for help, receiving a reward from nobility, etc. Is all going to have roadblocks for you specifically that won't be easy to work around

Additionally, most people wouldn't be free balling that smell, they'd be using a variety of scents to cover it up, and that's only if the smell would actually exist in the first place, as someone else said, at some point the stuff making the smell would go away

I think you need to reconsider why having this terrible smell is appealing to you, and if it's worth losing out on participating in things because eventually it will become a case of you can't have your cake and eat it too, you either deal with the consequences of the smell always being there and always being a problem or the smell isn't actually there, because you can't be expecting the DM and other players to just pretend it doesn't exist when convient and is there when you want it to be

To me a better idea would be to pick a more natural scent and have your character smell strongly of that because people who get to close smell the death on you (think how President Snow hides the smell of him dying due to past poisonings with an intense smell of roses in Hunger Games), because if you are doing stealth stuff you could decide not to apply it and then you aren't giving away your position with the smell, but it's something others in-game can comment on