I tried the folding hood and the reflex viewer approach to avoid my large heavy hot darkcloth, but despite it's disadvantages I found a darkcloth is the best approach for me for many reasons.

So I finally made a home made one which is nylon silverized fabric on the outside and black cotton on the inside so it is lightweight and reasonably cool in the sun. I have fit it to the camera and put velcro at various places to hold in the dark yet keep to minimum size and weight. It also serves to cover the pinholes in bellows and act as lens shade when folded forward.

Other than having it redone so it doesn't look so amatuerish I am very happy with it. Wish it was heated and airconditioned but that might increase the weight.