The clamps are ajusted using a bolt from the outside. No bother in getting them just right and also having modest tension on the 5mm wire..Firstly, I think that having the spreaders a couple of degrees down from their ideal position isn't worth losing sleep over. I did a quick calc and it's not until they're three degrees wrong that they'd even think about sliding even if there was no clamp. My keelboat has no clamps so the only thing that keeps the spreaders angled is the socket! And don't tell anyone, but they're only just above horizontal.
Secondly, it won't be quite that simple. You have some clamps in the spreader tips which you may be able to access from outside. Other types require the tip to have a retaining screw removed and the tip then extracted to get to the clamp. To do that you need to slacken the cap shroud significantly.
First thing to do then is find out what sort of tip clamps you have. If they're internal I'd leave it as it is.