> It’s clearly viable, but for that kind of DeltaV across such a long trip, solar powered Ion thrusters have several significant advantages.
Not really. The only potential use for ion thrusters is for cargo transport that is not time depended. If you do that you need to figure out how to do the landing, so the complexity is just higher. The thrust is just to low compared to a few powerful chemical engines. If you can refuel in earth orbit for cheap you are gone be way better off with chemical.
If you move on from chemical, nuclear thermal is by far the best option.
Food is really not the problem. The mass of food needed for humans is pretty small. Clearly you want to produce food on Mars eventually but its not a priority for the first 5 to 10 years. Refuel on Mars is by far the biggest mass saver.
For comparison the ISS’s solar panels are over a decade old and still generate 240kW in direct sunlight. So, you could easily reuse those panels for multiple trips, though power output is cut in half near Mars.
As to growing food, for on a single mission it’s not that critical, but if you’re sending several missions to Mars unused supplies from one mission can be used on the next mission. Further, the difference between survival and comfort adds up to a lot of food.