Span margin should usually only ask for the initial margin assigned to the futures contract. Like if your trading an outright futures contract. But, I imagine it also depends on what you're trading.
Less if its a short spread with the margin req being the handle count between the long & short strikes.
3x initial maint margin sounds steep. But, they can ask anything they like. They are the "house". & if they are a "fraidy cat" broker not used to dealing with short premium/gamma trades, they could ask for your 1st born.
I've heard that IB asks like $5000 per lot on a short option trade for Russell E-mini's.