How large are your mortar tubs? Are they the black 'cement mixing' tubs that are like 18'' by 24'' or something like that?
If so, those are fine for feeder tubs, just build an appropriate rack.

For a 1.4, I would recommend at least about 10'' x 20'' of floor space. About as large as a ten gallon tank. That should be enough space to keep everyone happy. So if your litter pans are about that size, they should be fine.

Some people leave groups together, and others remove the male, let the females have their litters and return the male when the litter is weaned. I would suggest removing the male, as you'll have much healthier litters, and mothers.
The male should be able to move back and forth from the females, with no issues.

Hope that helps.