Thanks Rand, I'll check out the videos.
---------- Post added April 19th, 2014 at 05:31 PM ----------
I purchased a DIN reg, but decided to use it as my main regulator and put my yoke reg on the pony. I originally had a 40" regulator hose but it was too long, so I put a 26" hose.
May I make a few suggestions?
Get some heavy duty elastic bands to use to hold the hose in place, like
these. You just need to buy one and then cut it down the middle to make two. They work a million times better than bungie cord, which you will find moves all around in the water and doesn't hold the reg and hose where you want it.
Bend the 6" hose back on itself and tie a short piece of cave line or bungie cord like this:
That will make the gauge more easy to see and it keeps it from slapping against the tank like it might in the manner you currently have it rigged.
Route the hose straight down from the first stage. You may need to cant the first stage so the hose routes straight down. When you use the elastic bands I linked to above, the hose stays really tight and you can use the hose to secure the mouthpiece in place, thus negating the need for the silicon mouthpiece holder shown in your photo (definitely lose that). This is what it should look like:

Also note the rigging for the tank sits about 45 degrees off center from the face of the tank valve. This allows the reg hose to route straight down the center of the tank and the hose then runs right next to the rigging, further helping to keep the hose in place. The whole idea is to have the reg and hose towards the outside of your body since the bottle should be worn on the left.
I can't quite tell from your photos if you are using a fuel line to hold the rigging together and provide some space for the elastic to be held off the tank. I'd highly suggest rigging it like shown on
Frogkickdiving.com if you don't have it that way already. As noted above you want the rigging to sit about 45 degrees off the center line from the face of the valve. Once you have the rigging set in the right position, pull down hard on it and tighten that hose clamp (also a word about the hose clamp, I'd get some tubular webbing for it to keep it from scratching up your paint). The rigging is NOT a handle, it merely keeps everything in place on the tank and gives some space for the elastic to sit off of the tank. You carry the tank on land just like you would any other tank, by the valve.
Note the elastic straps holding the hose. One goes over the rigging (this allows you to easily slide a finger under it when stowing the hose in the water), and the other goes below the lower bolt snap (you should have an inch or two on your tank to do this--if not, I would put both pieces of elastic over of the fuel line rigging and between the bolt snaps).
It's all nice and streamlined with minimal pieces, and it all stays in place with those elastic straps. When you need to deploy it, you just grab the second stage and pull up and away from you. The elastic holds it tight, but not so tight that you can't deploy it. You want it to stay tidy and not become an entanglement hazard.
Nothing says you can't use a yoke valve on the pony, but the DIN valve will stick out a little less and also be less prone to catching onto something. As you accumulate gear, consider getting another DIN valve for the pony. But I agree with you right now. If I only had one DIN valve, I'd put it on my back gas first and get one for the pony later.
Sorry if it seems like I'm tearing apart your rig. You have most of the pieces, you just need to clean it up a bit.