Will give this solution a serious look as it seems that a suspension fork might not do much for small bumps anyway - serious road buzz, in fact - under consequent load, which is what I really want to cure, to ride all kind of country paths and badly maintained towpaths but not mountain single trails.

Though it would be lying to say that I'm not seriously considering a Bob yak, which can be had used for a very decent price (half that of a rack+panniers setup, in fact...) and might allow a more relaxed handling over all kind of roads.

Thank you very much for these numbers, I'll try them as soon as I can!