Now that I've more time to think about the ordering of levels, I don't think the "shortage of easy levels" is nearly as bad as I at first assumed -- certainly not bad enough to justify keeping all or even half of the Tame levels. Surely we don't want to put new players through that yawnfest. The Fun levels present genuine challenges to overcome, so that the player feels they are building on the skills they learned in the tutorials, whereas if you can pass Tame 1 you can pass the whole set.
I would argue for keeping the special levels in the same spirit as they were originally intended -- a once per rank "just for fun" level. Doesn't matter that they don't fit the difficulty curve -- the odd breather level is much less of a problem than abrupt difficulty spikes.
Here's a draft order for a redux Fun set, to show that it could work with only a small number of Tame levels:
Training levels -- Either keep as they are, or, for a repeats-free pack, replace Fun 2, 4, 7 with 2P Level 33, Tame 11, Tame 8, and give those levels the skillsets and titles of the training levels they replace.
8 - Tame 1
9 - Adapt two-player level "The Pipe Room" (or Tame 5)
10 - Tame 4
11 - Fun 11
12 - Tame 7
13 - Highland Fling with 20 of all
14 - Go for it!
15 - Bridge Away!
16 - Tricky 3
17 - PSP 10 (Just 17)
18 - Fun 18
19 - Genesis Fun 19 (Catch more floaters)
20 - PSP 9 (Pillar talking)
21 - Through the graveyard
22 - A beast of a level
23 - Flow Control, remove red herring skills and have more lems to allow more leeway
24 - PSP 14 (Tunnel vision)
25 - Fun 25
26 - PSP 18 (The run around)
27 - Natural life
28 - PSP 20 (Lemming toast)
29 - Genesis Fun 29 (Dark dawn)
30 - Let me get out of here (of course, we should fix the pun: Lemmy get out of here)
...then there are quite a lot of levels on the late Fun / early Tricky boundary, so it would be easy to fill the set up if we decide on 40 per rank.