Got a pic of your transom?
I am a bit pzzled - does your engine cowl come flush with or sufficiently close to the top of the transom that you can't get the clamps over or will it foul something when trimmed up?
One curveball to throwe in at this point is most wee 4Hp or thereabouts "keepy uppy" mechanisms won't generally survive the battering they get on a transom.
I carved a lump of wood to put between my aux leg & bracket which holds it at an angle that Johnsorude never designed it to sit at, but at the same time be a lot more solid. I guess if you are balancing on top of an engine cover to remove it that might not be a good option for you.
OTher Q - you say drill? Is this because you don't trust the cmlamps? Fair enough, but could you do some trial positioning with the screw clamps before drilling?