You can reduce the amount of buying power selling puts in an IRA uses up by buying a cheap OTM put around the 5 delta area. This put should reduce the buying power reduction to the spread width instead of the full $37,500 and will somewhat approximate margin buying power.
Maybe I'm misunderstanding you. Are you saying that if I sell a 370 put but I also buy a 320 put at the same expiration, that instead of needing to have $37,000 to cover, I would only need $5,000 (the difference between the strikes)?
Initially that made sense to me, but then I was thinking say the price ends up being $360 at expiration - I would still need $36,000 to pay for the shares I get assigned. That 320 put is worthless - so why would buying it allow the brokerage to decrease the cash I need to hold for the 370 put?