Thanks for your reply, MattBearman.

According to ArcticSilver ( http://www.arcticsilver.com/pdf/appmeth/int/vl/intel_app_met... ) all CPU covered with an aluminium plate should have their thermal paste just put in a single vertical line in the center.

They also talk about the line surface spread method you're talking about but only for mobile CPUs.

My fear is that by spreading the paste with gloves I'd somehow add some air in the paste, resulting in really bad thermal conductivity.

It seems your method is the way to go, though: http://overclocking.guide/thermal-paste-roundup-2015-47-prod...