I have a somewhat used navigation manual dated 194
Yep put together by those navigation types that ended up running the CAA!
But it has a really useful little set of cardboard templates -with circles of 3 to 10 miles which fit a half million chart. Great fun to use and quite eye opening.
I have found them,or rather the knowledge of them really useful in smoggy conditions - they make you look for simple landmarks, things which cannot be confused, simple line features, features which do not rely upon prolonged DR headings but which give you a definite confirmation every couple of minutes.
With this sort of approach - no you do not need instruments, just a bit of planning. But if you want to fly 100 or 250 miles on a DR heading and then find the 'right landmark' then you are heading into the terriority of the Kingsford Smith's, Francis Chichesters etc.