If it is dry and draught-free inside, they should be fine with those arrangements. Hay is an excellent insulator so is ideal for bedding. If the bed areas are slightly raised off the floor eg on bricks, they won't get the chill from the ground. They probably won't need the heat pads unless it gets really cold. They have each other to snuggle up to.
Is the shed insulated? It can make a big difference, but isn't essential - it depends on the set up. eg. If the shed is under the aviary roof and not open to the wind, it will stay warmer anyway.
I always go by the water bowl - if it is frozen, they need more insulation.
I have a max/min thermometer hanging on each hutch in the main living area so I know just how cold it has been. I reset it every morning when I check on the rabbits. If it gets to -3'C outside, I usually put an extra layer of covers over the hutch. The water inside never freezes. I rarely use heat pads, but I tend to use them in pairs, wrapped in newspaper to keep the hay off, and put them near the bottom of the bed of hay. They stay warmer for longer in pairs than as 2 singles.