Another way would be to simply enforce the cap for the entire league year including playoffs, allowing for any possible overages only during the offseason while teams build and then once again become cap compliant before the next league year.
Like every other cap based league.
If you have to play even shorthanded at times during the regular season to be compliant, why would it all fly out the window once the stakes are at their highest?
It's not cheating per se, but its also intellectually dishonest to say that it cannot create an advantage if everything comes together with impecable timing.
My personal belief is that the teams iced for the playoffs should be cap-compliant based on their regular-season pay, as Vegas was last season by sitting a number of players such as Quick.
Whether the NHLPA will go along with such a rule is another story because of their interest in seeing as many players paid as much as possible, and of course the NHLPA hates the cap in the first place anyway. I'm also skeptical that a majority of GMs and owners will go along with it as well. If there are any meaningful changes, I seriously doubt they will occur before the next collective bargaining agreement.