couldn't somebody, in theory, add a couple more rail bolts per rail, screwed into the slate from the side just as the originals are?
although i guess it would make me nervous to swiss cheese the slate any more than it is already...
either way, i personally would have a hard time with the ethics of altering an antique to that extent. perhaps it would be better to have a duplicate set of rails made, so you can alter those and not the originals.
Yes, extra rail bolts could be installed if one wanted to go through the all the extra work to do so. And yes, Mark is right, there is a way to add the extra bolts from the bottom side of the slate up into the bottom of the rails, but not a chance in hell someone would want to do it that way just to add more rail bolts
Glen