Hugs Liz - phew, sounds very tough to deal with that on top of everything else
I was also going to suggest doing the main meal at lunch time (if you are at home, of course)
My boys have always eaten their main meal at midday. I find they eat much much better and then I know that once the cooking and clearing up is done I only have to make a sandwich/snack at teatime with a glass of milk - I
hate having a kitchen full of saucepans at bedtime.
Nicholas's behaviour is always dreadful if he hasn't eaten - I ALWAYS know if he hasn't eaten his snack at school by his behaviour on the way home
And I'm sure you've tried this - but have you tried a drive around on a particularly bad day - will he nap in the car?
Or lying down with him in your bed while Meg naps? Maybe do a long story first?
Hugs. It will get better