Hello, I'm sorry that I've come to this thread rather late.
I bought the Kendal 4 ft hutch because that was the largest we could fit in our tiny garden. That is already the minimum size (unlike your 5ft one which will be much better) but do bear in mind that the dimensions of that interior will be much less than the exterior ones -- and the manufacturer is measuring the overhanging roof to give these measurements (unless they now also give the interior dimensions as well).
Perhaps you have been luckier, and the hutches have been improved, but I was really unimpressed with its quality, with a bowed and flimsy roof and equally thin back wall and floor. We fixed a more sturdy layer of plywood to the support struts which are on the outside and 2cm deep and packed the gaps with insulation to turn it into a decent, solid hutch.
