Lack of WCML – Kent advance fares

Is there any way of doing a day trip from Hemel Hempstead to eastern Kent (Ramsgate, Sandwich, Dover) for under £40 return (with a 16-25 railcard)? Looking at Brfares.com for what's theoretically available, Watford Junction (not necessarily Hemel) has advance tickets for the coast between Weymouth and Bexhill, but not into Kent, and St. Albans has advance tickets available to Kent destinations. (Having found St. Albans – Kent advance fares for £13 and only thought of this option whilst writing this, I think I'll probably do that.)

I could understand WCML to Southern and South Western destination fares being explicitly introduced due to the option of going via Clapham Junction, which makes less sense for Kent; is the omission of advance fares to Kent, which I know is hardly a unique case in the fares system, likely down to intent or accident?

Semi-flexible walk-up Off Peak Day Return at £43.40 (with Railcard discount) from Hemel Hempstead to Sandwich (or to Ramsgate or to Dover Priory) is possible. Routed ✠VIA LONDON. Valid on trains arriving into London at or after 1000 (midweek).

Cheaper Off Peak Day Return fares available from St. Albans City at £32 35. Routed ✠NOT VALID ON HS1. Similar time restrictions.

Mcr Warrior said:

Cheaper Off Peak Day Return fares available from St. Albans City at £32 35. Routed ✠NOT VALID ON HS1. Similar time restrictions

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That doesn't seem particularly unfair price-wise, although I think I'll go for advance fares as I'm looking at weekdays a few weeks ahead and want to get there considerably before noon.

Alternatively split in Central London:
Hemel Hempstead to London terminals Anytime Day Return £18.60 (16-25)
London to Sandwich Super Off Peak Return Route Plus HS1 £28.70 (16-25)
Total £47.30
Valid on 10.07 ex St Pancras arrives sandwich 11.38
You'll struggle to find Advance fares on Hs1 before 10.00 except maybe on fridays in my experience.
There's cheaper options on "not hs1 fares" ( but not by much) and you wont arrive before 12.00