insofar as there's absolutely no way boeser is going to agree to a 4-5 year deal for below $6 million,
i think lowest possible value is you trade him as a pure rental to a contender. if you eat salary, which why not, you should be able to get a late first and an A-/B+ prospect. given that that is also boeser's most likely value, i think you take that as your baseline for a deal.
the highest possible value, which imo is also the most unlikely, is a bad team wants to invest in boeser and is either willing to qualify him and then negotiate an extension or blow him away with an extension offer that he'll take before playing QO chicken to try to hit that number or UFA status early. the problem is that's a trade you do at the draft, not the deadline. the bad team that wants boeser probably doesn't need to pay the premium to have him for this year's playoff run.
so i think the extra value with the boeser asset is the team he's going to having first right of refusal to his RFA contract. that also means holding his rights at the draft. i think best case scenario is tacking on something commensurate to that value onto a deadline trade to a contender, which they can later recoup at the draft if they trade him to seattle or something.
i wouldn't have expected benning to be able to see these variables, let alone act on them in a timely manner, but i'm guessing rutherford/allvin should.