Is there a downside of using CSPs to acquire ETFs I want to hold long term?

So, long story short... I have some concentrated positions with massive capital gains that I'm working on drawing down and diversifying. My current practice is when I sell, I take 35% of the realized gain and immediately park it in SGOV for estimated quarterly taxes, while taking the rest and immediately buying VTI. (35% chosen for 20% LTCG + 3.8% NIIT + 9.3-10.3 CA tax.)

VTI is planned to be long-term buy and hold until retirement (best-case, 9 years away).

I'm considering a strategy, instead of immediately buying VTI, of parking the money I'd use to buy VTI into SGOV and then selling OTM (but near the money) CSPs on VTI to collect premium until being assigned and thus buying VTI at a discount.

VTI closed yesterday at 362.74. Right now, Jun 18 expiry puts at $355 strike are paying $3.80 premium, or a 1-month yield of 1.04%. Annualized (although I know being that close to the money I probably wouldn't avoid assignment that long) that's a 12.6% return on top of the 3.91% currently for SGOV, or essentially about 16.5%. The goal would be to continue running it at a convenient premium in the \~1% monthly range until assigned.

I look at it this way...

* If assigned, I'm only really "hurt" if I'm assigned at a price of $351.20 or lower, because that would be my cost basis. But if VTI drops to say $345, that's still better than buying it at $362.74 and riding it down to $345, which is what I planned to do as it's a long term play. And it doesn't hurt that much, because I can buy more shares at $351.20 than I can at $362.74.
* If not assigned, I'm really only "hurt" if VTI runs quickly and I miss out on those gains. I'll have to chase it up which means shares are more expensive (so I can afford fewer) but has the advantage of if I get assigned, it's probably at a higher cost basis which reduces taxable gains down the road in retirement. The only way I'm really hurt is if I continue avoiding assignment somewhat long-term and VTI's returns exceed the \~16% of this strategy--which isn't unheard of given that VTI has increased >24% YoY.

Seems like an easy way to juice the return for something I was planning to do anyway...

But I trust that you're all going to be able to point out some massive thing I'm missing here ;-)

(Edit to add one more point: this isn't a realized income strategy--options premium and SGOV dividend would be used for additional investment.)