My understanding is that his $30M salary this year is already guaranteed. It's his $29M salary next year that becomes fully guaranteed if he's on the team March 13th.
Let's just ignore the per game incentives since they're under $1M each year.
The way I see it is you'd add him his year and convert his $30M salary to signing bonus that gets spread through 2029 (4 years). So you pay him $30M, he counts on the cap for $7.5M.
In 2027, you convert his $29M salary to signing bonus that gets spread out through 2029 (3 years) again. So he counts $17.2M on the cap ($7.5M of his 2026 comp pro ration + $9.7M for this new 2027 pro ration).
In 2028, he'd have no more guarantees left but due for $26.5M salary. The cap hit would be that plus $7.5M of pro ration for 2026 comp and $9.7M of his 2027 comp... so $43.7M total. That's obviously high but not insane. You can convert some of that $26.5M salary to bonus too.
In 2029, you can trade/cut him with palatable dead money of $7.5M from 2026 pro ration plus $9.7M of 2027 pro ration ($17.2M total) plus anything you pushed back in 2028.
So all in all, I see it as us acquiring him for 3 years (2026-2028) and $85.5M with $17.2M of that cap hit being deferred to 2029. And then add in the <$1M per year in incentives and possibly pushing more money into 2029 depending on how they approach 2028.
Obviously you have to make the right go for it moves around it because that is definitely building with some degree of short term window, but I think it's palatable.