I would say that you've got a fairly good idea of items to put on your 1st line rig/belt. About the only thing you really can do is try a few things, experiment as to what you prefer.
3 gun matches and training courses are a good way to try out what works well for you. Many people will change around their gear as the mood strikes them.
About the only thing you need to watch out for is overloading your belt IMO.
I like suspenders, even though my padded Eagle belt is fairly light. That way the belt doesn't have to be very tight-more comfortable. But I use a PC for matches, rifle courses and work back up. I personally don't care much for drop legs on each side.
Since I have a 6004 drop leg for my pistol (keeping that similrity thing going with issue stuff) I have a personally owned 6004 for fun/training. Besides, I'm not supposed to take issue gear (ie vests, holsters, etc for personal usage/training.
You might be better off IMO, with a G23, to use a belt holster of sorts that is similar to where you would normally carry-then when you get the G35+light, you won't have sunk a lot of money into a drop leg that's only back up at best.
A belt with a couple of mags (rifle and pistol)in pouches, dump pouch, holster, knife/multi tool is not overly taxing IMO.
The padded belts are nice, but spendy. You can go that route, or you could also try a chest rig (Eagle/SKD's product) is quite reasonable and gives you everything basically, except the dump pouch, for about the price of a dop leg holster (at least not the spendier ones).
Good luck and have fun.
And thanks for your service.