I tend to think you'd be better off making the game much shorter if you wanna do zero respawns. Eliminate the need to build a stronghold, put gear and refined material drops on enemies and in dungeons, maybe flatten health and damage progression since you're just eating whatever you can find. Food plants and beehives would drop food instead of seeds or queen bees. Probably do away with enemy respawning in areas, so you have to keep moving to progress. To enforce haste, invasions would probably follow you around, growing more and more frequent until you eliminated the next boss.

Get all that done, condense the game to a two hour or so experience, you'd have a pretty sick (if basic) roguelike mode. Might make for a good mod.