I tend to have to wash everyday because he wears wool or fleece to bed anyway so the smell transfers.
Bamboo is the most absorbant thing out there. Possibly adding some microfibre boosters in between the two nappies would make it slimmer and more absorbant than the terry booster - bamboo boosters would be better than the terry too.
Wool shorties would work better than the fleece wraps probably - need much less washing, and that much more stretchy to fit over all the bulk.