Not at all, OBK.
If the viz is on the low side, simply fly a DR tack for a certain amount of time. Take a good look at your chart and decide in advance what features you're going to use to identify your position - line features are particularly handy since you'll definitely overfly them - but if you miss a feature, particularly in low viz, don't get stressed about it, just wait for the next one. It might also be worth routing slightly differently to ensure that you overfly easily-identifiable locations such as large towns, depending how confident you are, and how far off track this is going to take you.
Like I said, the only time I have been unable to find enough features to be happy was in the desert. And since I live too far from the desert to make a habit of flying there, I view that as the exception rather than the rule for my type of flying. I've flown a hundred miles or more in 5km viz without any trouble at all. If the viz really is that low, I'm generally more worried about it decreasing so that I have trouble maintaining straight+level and spotting traffic than I am about navigational problems - I would stay on the ground or near my home airfield unless I had confirmed reports that it was improving.
FFF
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