I use the Galls Flexible Waist Belt. I've used it for the past 15 years and I've been completely satisfied and it keeps my shirt tucked in.
Shirt stays best thing since sliced bread.
sew them to your socks
yep sock shirts work great, kinda like a onesey for big guys... heck i just mite invent something like that,
( police onesey's) hmmmm
These days my uniform consists of a polo and 511 pants, so stay nee around the waist isn't and issue, but when I was wearing traditional uniform, I used shirt stays. That is, until one broke loose and there was a nasty grazing incident!
Having the final tayloring done with your vest on (You do wear your vest, right....)goes a long way towards proper fit.