Gammadoodler
Hero
I don't know how specifically you all are planning to build out potential encounters, but if you are using actual monster statblocks then those monsters could have an aggregate outgoing average dpr. Assume a party size of 4(or whatever) and divide evenly or apply a weighting?To me it falls under the same consideration process as enemy control effects (more likely to impact the fighter).
It'd be a cludge, but might be a decent litmus in a "if x% of damage per round goes to the wizard they go down in y rounds vs the same for the fighter" kind of way.
Edit: though assuming on demand healing and no lost actions to unconsciousness isn't really that unreasonable for a D&D party.