Hmm.
Obviously you are evil and don't love your children
but I see the dilemma of not being able to afford buisness x 4 but your DH fretting about not getting any sleep and then going to work.
I think you'd have to:
a. Look on it as buying 2 x business and 2 x economy and everybody gets to swap around, with key sleeping time for DH in business accompanied either by you or a child SWORN to silence with the aid of electronic goods.
b. One seat in business, 3x premium rump steak economy, adults take turns occupying the business seat with DH having it for a key few hours of sleep, while the other 3 get to sit together. That would be much nicer, really. And cheaper!