Most efficient use of lump sum into pension

I sold a rental property last year. After fees and CGT, I have around £33k currently sat in a savings account, and wondering what is best to do with it.

I am employed FT and earn just under £50k + bonus, I have been upping my SS and making extra payments into my work pension to avoid higher rate tax on bonus and the rental income. Rental income for 25/26 will be fairly trivial as it was empty much of the year ahead of the sale. I can comfortably pay my bills and into savings at this income level.

I'm late 40's and (only) have around £50k in my pension, plus a DB pension from a former job that will pay just under £4k pa. I have cash & S&S ISA's, no debt other than mortgage and nothing I am likely to need it for any time soon - it's definitely money for the future.

The most obvious solution is to deposit it into my pension and reclaim the tax (I would likely do £24k plus £6k tax so £30k deposited, and leave the rest in savings).

If I do this, is there any need for me to do so before the end of the current tax year? My ISA allowance has been used but my wife's hasn't, she is due to receive a lump sum from an inheritance during 26/27 so I thought to put £20k in an flexible ISA in her name that she can return once she receives the inheritance and effectively have a £40k allowance next year.

Alternatively I have considered upping my salary sacrifice to just under 49% (I understand you can't SS to below minimum wage) which will pay almost £2k per month into the pension and save loads in tax, and then pay myself the shortfall in wages from the property money, for the next two years. This will let me pay about 19% more into the pension over the 2 years (compared to adding the £30k upfront and continuing my current 10% SS) while still only costing me the same £24k in topping up my wages (£1k per month) though of course most of it will have less time to appreciate. if I do do this, I will ask if my employer will split their NI saving with me, which I am not optimistic of in all honesty but would be another pro for this idea.

From my calculations, the annual growth would have to be well over 20%, which seems optimisitic, for the compounding effect to be such that a lump sum would exceed the upped SS.

I know "time in the market, not timing the market", but is that what this is? I would get more growth in the two years just leaving the lump sum to grow, but the tax and NI saving benefit would likely exceed the growth and overall I'd have more saved by the end of the two years. This also feels like quite a turbulent time to be depositing such a large lump sum.

Would be grateful for thoughts on this, especially if anyone has done something similar! 

Thanks for reading if you made it this far.