I need a convenient carry solution for quick access when I cannot wear a nice belt holster. For example, I would like to:

1. Have a gun on me while pumping gas after work (where I cannot carry)

2. Have a gun more accessible when driving (in tx i cannot use a visible holster attached to the car.)

3. Walk from my car to front door armed

Ill be carrying the Glock 31 or Glock 40 this way.

I am thinking an open carry shoulder holster with no retention is the best solution. Another would be a clip on belt hokster but i dont think that would be realistic to put on sitting down in the car, especially with a dress belt.

Open carrying a shockwave or AR pistol would get me more attention than I want.

Thanks in advance for any suggestions.

Tanker holster.  These are also great for hiking/hunting/fishing.  Amazon Tanker Holster

Shoulder holsters are too easy to get tangled taking them on and off.  Sometimes one side is looped through the arm-hole, the whole thing is backwards, both sides are looped....   You will find it very frustrating to don from a sitting position inside the car.  

I suggest a paddle style holster.  They don't conceal well, but then concealed isn't on your list.  You can even use a paddle holster without a belt as long as you aren't going to be running or going inverted (assuming the gun isn't overly heavy).  Some of the plastic paddle holsters have barbs to hold them in your pants so they don't follow your gun out, but those can be filed off.  A tightly fitting holster or one molded tightly to the gun may give you some trouble when you try to draw, so you may need to tinker with it (thus rendering it to your specific purpose only).

In this case, I would say go cheap.  Get a 'universal' paddle holster and make adjustments to the holster and paddle until you can easily put it on and take it off from behind the wheel of the car.

I'll second paddle holster. it's not too hard to snap it on either seated or just while getting out of the car.

I am curious why you say you can't have a holster mounted in your car in Texas? I've read the laws and stuff and don't see that mentioned anywhere. I have a holster mounted in my console and used to have one under the steering wheel.

A lot of times I just keep a gun in my center console for quick access when driving. Too hot in Texas for a shoulder rig and cover garment usually. I like the shoulder rigs in the winter though with a jacket. Usually I just go with a pocket gun or IWB compact gun to hide easily with jeans and a t-shirt. While I'm not a huge fan of ankle carry, it is easy to access while siting down driving, and it conceals well. But yeah since your guns are large I'd just go with the center console. And get some smaller guns for conceal carry.

Your car falls under the Castle Law.  If you have a HL you can have it wherever the Hell you want OC is legal.  If you do not have a HL you just have to have it covered out of sight and when I say covered you can literally have it covered by a towel on your dash that is legal.  You should brush up on the Texas laws it seems you have very outdated information older than 2011 laws.

Tanker holster is easy to put on and take off from just about any position.  They're also good at weight bearing and are comfortable driving.  You can choose to use the chest strap or not.  On the other hand, something like a Galco Miami Classic, a very different design, is a PIA.  

Agree that you need to take another look at Texas gun laws.  They've changed in the last few years for the better.