I reckon it`s do-able [keeping your temples ] .... you can make a template so that the edge / perimeter is back a bit ..it will be necessary to get the density of the system fairly spot-on there or it could be a give-away, but yeah, I can see why you`d want to keep them.... you should check out JRob`s site ` Hairjive.com` --devoted specifically to fullcaps... he`ll also be quite happy to deal with specific points/concerns you will have. I`m not too sure what you mean by asking will the system ` hold up for 12 hours at a time` ....if you mean bond-time, 12 hours is nothing... most guys wear for a minimum of anywhere from a few days to 2 or 3 weeks...depends a lot on your lifestyle - regular gym-goers will be sweating a lot and need more frequent de-bonds/cleaning as adhesives will not hold up so well to heat and moisture,and the need for hygiene for the scalp, as opposed to a person with a more sedate lifestyle. Personally, I only do a light bond [a few small/short strips of ` Walker no-shine` tape, and remove the thing nightly, but that`s just me, and not everyone has the time for such frequency] You`ll also need to 1 experiment` a bit and find out which tapes/ glues work best with your individual body-type....so a bit of trial and error is normal for everyone in the early days of wearing. Many guys use ` Got2beglued` spiking glue as a bonding -material....it has it`s uses....won`t hold up well to profuse sweating, but it`s quick/easy to apply to the scalp, will hold for about 2 days or so, just hop into the shower and let the water at it and it`ll release.....rinses out / off the lace and scalp really easily....doesn`t hold the very edge of the perimeter too well I found, but all I did was use 2 or 3 strips of tape at the very front hairline to ensure no visibility [lifting of the lace] and `Got2b` over the rest of the head...works just fine....mostly though I just use a few strips of tape here and there at the ` strategic` points, and leave the rest of the scalp un-glued/taped---leaves the scalp ` breath` .