A swing arm is going to be the easiest way to achieve enough articulation or drop and still maintain suspension geometry.
An a-arm type has constantly changing camber so the camber will only be correct at 1 height. All other heights will produce undesired positive or negative camber.
That is ok if the suspension is only changing when hitting a bump, not so ok when it is contantly rolling at a different height. Then you would want some kind of load proportioning air valve to maintain a set height under various loads. More hassle. My car has 4 way air suspension and those load valves. They require maintenance. I do find it "neat" that the OE decided to put a 3 way valve down on the floor board including a "rough terrain" position. Even then, excess tire wear will occur if operating in that position for any length of time. Same if operated in the "dumped" position. Then again, bigger problems like oil pan wear would occur much quicker.
That's not to mention excess ball joint wear and many additional bushings required for a double a-arm. You have atleast 4 bushings and 2 ball joints per wheel....as opposed to only a single bushing on a swing arm.
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Here are some example stub axles to consider
$18 1,750lb cap ea Standard hub/bearing provisions. No brake/backing plate provisions. 8" long, 1.75" diameter (part to be welded)
If that 1.75" hole was bored into your square tube "swing arm" and precisely welded, you might be good to go. Needs to be square or you will end up with all kinds of alignment problems. Take it to a professional to be jigged and squared.
Another one of these (or similar) can be used on trailer frame end to serve as pivot. Provided you supply proper bearings and hub housing. Or it could be bushed.
Here is a different model for $30 with brake provisions