"We're the Sultans of Swing."
Also an ounce weenie, but the 'biners also attach my Camelbak to my pack, so...
"Just prepare what you can and enjoy the rest."
Old Rag -
That's not a Marlin spike hitch, unless I'm mistaken. You've got the 'biner larksheaded onto your strap?
The knot in the photo isn't this,
but it looks like a variation of it. Found it per Bubba. And instead of putting it over the knot, maybe just clip it into the biner, ie. more secure?
I'm thinkin biners are only strength-rated when the load is placed on their long axis...Prob'ly doesn't matter here cause you're using the Knot- Not the toggle...
Maybe replace that biner with a 23g Camp USA Nano biner; MSH the biner to your straps; and just hook your whoopies right into that biner? Been working for me many hangs... Also makes a nice place to clip your backpack light, etc. Either way HYOH
"Climb the mountains and get their good tidings.
Nature's peace will flow into you as sunshine flows into trees.
The winds will blow their own freshness into you, and the storms their energy,
while cares will drop away from you like the leaves of Autumn."
— John Muir
I have used a carabiner as you described many times and yes the hammock can be directly attached to the carabiner.
If you use a strong 'toggle', say a piece of steel, there is no reason you could not put full rated load directly on the toggle. The reason a lot of hammmock folks say not to do this is due to the weakness of the toggle, not the marlin hitch itself.
Here's a real marlin spike FYI