Interesting Huvius. Nothing good has EVER come from using that thin a patch. You are right in that more lube will be needed - as you will not be able to load the next one unless the fouling is softened by the lube. A .010 to .015" patch in that size gun will not carry enough lube by itself.
Some guys have luck with wads, others not.

My own 14 bore cares very little for imperfections in the load such as added 'stuff', but does not need them.

What I mean by this, is that as with modern rifles, the larger the bore, the more imperfections the gun shrugs off as being immaterial.

When loading, mount the sprue straight up or as straight up & centred as you can get it before pounded the ball into the muzzle. Slight imperfections in that will not mean anything.

You might also look into getting Jeff Tanner to cut you a .712" mould. It will be cut at .712" and cast at .710" to .711".
Jeff's moulds do not have a sprue cutter, so I use a pair of "cupped" wire strippers to pinch, then twist the ball and the large sprue comes off leaving a perfectly round ball that does not need orientation at the muzzle for loading. The odd ones needs a swipe with a coarse rasp to smooth the little tit of lead sticking up.

Balls cast with a Tanner Mould

Jeff's moulds fit standard handles.
Oh yeah - one further thing - I now spray ALL of my moulds with MsMoly for bullets or Lyman's spray moly for bullets(same thing) or use Rapine's "Mould Prep" on my mould blocks. The moly or the graphite in Mould Prep prevents lead sticking to them and eases the ball or bullet's release from the mould.