For years UK special forces have used 'low-riding' pouches that hang below bergan / rucksack waist belts. You can always modify your own pouches to be like this or buy one from this source:
http://www.sass-kit.fsbusiness.co.uk/Look at the page on 'Webbing and Pouches' and follow links to see the features of SASS own pouches.
A cheaper alternative is to track down British '44 pattern water bottle covers. These had the same low-riding atachment and were so popular in later years that it is rare to find '44 webbing sets being sold with the water bottle carrier. Before the PLCE webbing came out, my webbing consisted of two ammo pouches, two '58 pattern water bottle covers with a modified opener(for my water bottles) and three '44 pattern water bottle covers for the rest of my belt order. They were excellent. Don't know if this will help, but at least you can check out the SASS website and get some ideas.
Cheers, Scott