I ga-ron-tee if you use piano hinge as a latch you will have zero bulging at any corner of your oil door.
One of my lasting regrets with how I did the 6A oil door 25-odd years ago was those kit-supplied elevated wing latches catching my hand and the polishing cloths every daggone time I worked around the upper cowl. Flat profile is the only way to go here.
I won't keep beating this drum but I am very happy with the combo of gooseneck flush hinge and piano hinge flush invisible latch. Easy to implement, secure as a vault, totally flush and smooth, zero cost using building scraps.
Hop-Along Aerodrome (12VA)
RV-6A - N30YD - Built '98 / sold '20
RV-10 - N130YD - Phase 1 flying
donating monthly to the VAF - thanks, Doug