To your point I'd assume a roster of 22 players would likely breakdown as follows: 13F, 7D, and 2 G.
With Weegar's contract included, Cap Friendly shows 8.3 M Cap Space remaining, with the roster being comprised of 10 F, 7 D, and 2 G.
To fill out the 3 F positions, not counting any player acquisitions, I'd project the following:
Saarela, as you suggest, at +/- 800K Cap hit.
Tippett at +/- 860K Cap hit.
Either Eetu or Borg, for added depth at C, at +/- 900K Cap hit.
If those 3 are added to complete the F roster, their $ would add about 2.7 M to the CAP, reducing the amount available to about 5.6 M.
IMO Hoffman / Duclair / Killorn doesn't seem to be realistic without some other move.