Kallen & family may decide that they need more fridge/freezer capacity, however your suggestion certainly makes more sense than a 50 & an 80 power consumption-wise.
Ours are 60 an 35.
Smaller units are more efficient. i.e.. in the same conditions, with same thickness insulation a 40 litre will use less than half the power that an 80 litre will.
About 'stuff' in general:
It is common for folk who are used to relatively large fridges at home to think they need a large capacity fridge/freezer for fulltime life on the road. Generally speaking this is not so. When travelling there are shops just about everywhere to re-stock from. By trying to 'transfer' home life to 'on the road' life, it is possible to make some expensive mistakes. Large fridge capacity is one of them. It's not just the fridge, but also the the system to power it which costs.
It is actually amazing how little you need to live on the road, & anything extra costs extra, both at time of purchase, & in needing to cart it around. Until experienced at living on the road I feel it is better to leave with a minimal set up & unused space. If you find that you really need something you don't have, it's no different buying it once on the road than it is to buy it before you leave. Another common mistake many make is believing that because they intend on being on the road full time that they need a huge caravan. Again imposing 'home thinking' onto 'on the road' lifestyle. Just recently I heard of a couple who had planned their travels for years, & 6 weeks into their dream trip they were miserable & stressed. They were finding that their new 24' was just too restrictive & unnecessary. They sold it (at a considerable loss) & bought an 18 footer in which they were much happier, less stressed & able to go to more places. An expensive lesson learned.
After 18 months living in our 7 metre bus we returned to our modest little 12 square house & all our 'stuff', & felt lost in all the space & belongings. Of course within a couple of months we had re-adopted old ways of being. When we eventually get back on the road I'm sure we will quickly adapt back to the minimalist lifestyle once again & wonder why on earth we needed 'all that stuff' back home.
Cuppa