When I batch prime, which admittedly isn't very often, I siphon directly onto the sugar solution and ensure the discharge end of the siphon tube swirls around (without splashing) so as to get the sugary liquid mixed into the incoming beer. When there is about 5 litres total in the FV I stop, but when the bucket is full, give things a gentle stir with a sanitised paddle to finish the job. Personally I am a firm believer in 'needs must' in brewing and trying to cut out some steps for fear of them causing you problems, may in fact create more problems in the long run, and a gentle stir in this case falls into that category.