i used to have a dunstall guard ( fibreglass, hose clamped to the top of the sliders) on my K2, which is about as stiff and bracing as a bowl of lukewarm custard, you could look down while riding on a rough road ( so most of the ones round here ) and watch the forks flex a couple of inches at the wheel end and not necessarily at the same time or rate
if you're worried about that sort of thing just don't look, didn't seem to make any difference to handling compared to having a steel guard, and to be honest at their peak these bikes handle like sh1t anyway, if you're after razor sharp levels then try a modern two wheeled anything, most uber delivery mopeds probably handle better