They will ask for no verification, but there really isn't a Guest Assistance Card (GAC) for bypassing lines. They will either have a quiet place to wait, or an alternative entrance with a waiting area, otherwise they will recommend using the fast pass system to avoid long lines. Sometimes you wait longer in the designated quiet waiting areas than you would in the regular queue. You may want to consider one of those walkers with a folding seat built in, then you can alternate between standing and sitting.
That was what I was going to recommend too.
They are called rollators and you can find them for sale for prices from under $100 to about $600. The price difference is mostly in things like how cushioned the seat is, brakes, quality of wheels.
Using one of those would allow you to sit when you need to sit and stand when you need to stand.
Besides Fastpasses, another thing you may want to look into is touring plans like Tour Guide Mike or RideMax. Those plans can help you to be in the quietest part of the quietest park. Many people have written that by using Fastpasses and touring plans, they got into everything without waiting more than 10 minutes.
The other thing to think about is how big WDW and how many miles the average guest walks per day - most are 3-6 miles, but can be up to 9!
Thats the reason that WDW recommends using a wheelchair or
ECV if guests are worried about walking and standing in line. The lines are only a small amount of the walking and standing a guest does during a day at WDW.
Just to walk around World Showcase in Epcot is over 1 mile. Some lines are a long distance - from the line entrance at Soarin until you get to the boarding area is 1/4 mile. That is just to get in and it is an equal distance to get back out. A GAC wont do anything to shorten those distances.
And, there are many attractions where guests DO have to stand with no place to sit.
Here is a link to a thread about attractions where guests wait and there is no place to sit.