30A Male to two 15A Female Y Adapter - where is it...?

I take the 30amp power cord into my Van and plug a 4 gang GFI box into it. The GFI box gives me four 110vac outlets that I plug my Micro, fridge, tv, light and window ac into as needed. The same 4 gang box can also plug into my 900watt inverter when boondocking (not for window ac tho). Not a perfect system but works well for me. Usually there are 15amp outlets at most camgrounds which I prefer, but sometimes I have to use the 30.