My few helicopter hours were all logged as flight test observer (well apart from those few minutes on the end of a bit of string under an S61

, I didn't think those were loggable since I wasn't handling any controls ).
Very early in life I had the sense to buy a commercial logbook. As I flew different types, I started with colour coding but it became a pain, so now I make up stickers on my PC and changed the column headings.
So, the headings of my (modified!) Pooleys commercial logbook (from the left are)...
(1) Microlight 3-axis, dual
(2) ditto, P1
(3) Microlight weightshift, dual
(4) ditto, P1
(5) Light Single, Dual
(6) Ditto, P1
(7) Motorglider, dual
(8) Ditto, P1
(9) glider, dual
(10) ditto, P1 [Not including engine failures!)
(11) Night
(12) IFR
(13) Flight Test Observer
(14) Spare (but used to be ejection seat flying)
CAA have seen my logbook a few times without raising their eyebrows at the method, and it's neat and easy to understand. Every few years the pattern of my flying changes, so I simply do an overall summary, and tweak the headings slightly with a clear note at the top of the page that I've done so.
As an approach it works quite well, and most logbooks can be adapted in a similar way. Pritt stick seems to be the best glue for attaching the stickers and use the thinnest bright inkjet paper you can get.
If anybody wants a copy of my Word document for sticking over the existing headings, please just ask (but you'd best Email not PM, or I won't have your Email address to reply to).
G