Alternatives to Paddling - Crossword Puzzles

I've been working on building a crossword puzzle, related to kayaking.  It seemed like an easy enough idea to start; kayak, canoe, lake - they have so many letters in common.   But, like all of life it turned out to be far more difficult.  Sure, it would start easily enough, but then I'd need a word that started with dk and ended with zt.   Anyway I preserved, (lots of ice and below zero days makes that easier to do) and now I have this:

It''s not perfect.  There are two two-letter words (rules require three letter words); one square does not have a secondary clue at all, and several clues are obscure.  But it contains a lesson I learned, so I thought I'd post it here.  Enjoy!

The clues:

Across

1.  Not weak or soft

5.  VW model

10.  Western Hemisphere Org., initially

13.  Dull, continuous pain

14. Archaic wanderer

15.  Apple seed

16.  Part one of lesson learned while making this

18. Wrath

19.  New in Bonn

20.  Compass dir.

21.  Oft thought while creating this

22.  Part two of lesson

25.  What Sting did with Edin Karamazov

26.  The desire for this ruins many kayak rolls

27.  “Monic” and “thin” follower

28.  Large, dark birds

29.  1947 Dennis O’Keefe movie

31.  Moved quickly

33.  Employ

34.  State not to mess with

36. Low light level

38. Not to be left unturned

42.  Part three of lesson

44.  Part four of lesson

45.  Discovered on a Scrabble word site.  Also a Roman cloak

48. Poor paddling alternative, initially

50. Baffinpaddler’s lake

51.  Enlist for a third time?

52.  Part five of lesson

55.  Father of Aoris

56.  One paid to kayak

58.  Glee’s Michele

59.  Part five of lesson

60.  Prophet

61.  Can’t do it

65.  Zorba recites the alphabet?

66.  Laud

68.  Iranian currency

69.  An aid to golfing

70.  Final part of lesson

Down

1.  60’s awesome

2.  Ward for the very ill, initially

3.  King snout-horned beast?

4.  Homer’s River

5.  Middle Brady girl

6.  A kind of moth

7.  Elf stunt double Ty

8.  A distinct pitch

9.  Adams or Poehler

10.  Drug containing opium

11.  USAF guys

12.  Disburses

14.  One who sees

17.  Period toward evening

21.  Fancy bedspreads

22.  American suffragette

23.  Of the ancient Mariner

24.  Two words which can finish this sentence:  “To shape a dugout wood you could use an ax --”

25.  Beverage made of yogurt

28.  Symbol for Ruthenium

30.  Italian city

32.  Zero

35.  Takei’s memorable role

37.  Allot

39.  Just one

40.  US Ocean Org., initially

41.  Abbrev. list enders

43.  Electric bug killers

45.  Former PLO chief

46.  NHL Flyer’s coach

47.  A fruit and a color

49.  Put a price on

52.  A type of waterwheel

53.  Fair type favored by the SCA

54.  Maldives money unit

57.  As ye sow, so shall ye …

60.  Luxurious retreat

62.  Storage container

63.  Fall behind

64.  Spanish article

67.  Neighbor to WY