What if I added addition support to the frame
(tubular crossmembers, x bracing, boxing)?
I have the means to make a 1/2 ton frame stronger than a 1 ton frame
Probably easier to just swap frames, maybe while I'm at it just add an additional frame support in the middle or where I see fit.
Merely adding a bunch of bracing/boxing/support/crossmembers/whatever does add additional strength to the frame in the sense of , and "beefing it up" will very likely cause it to fail sooner than just leaving the 1/2 ton frame alone if you plan on loading this truck up like a 1 ton, either with towing or with cargo payload (though it's unlikely you'll shove enough cargo in to the back of a Suburban anyways to really even stress the 1/2 ton frame).
This is very common misconception among MANY people - that bigger/beefier/more support equals stronger which in turn equals better. This also follows for most people that assume that a C-section frame is weak, with a fully boxed frame being bulletproof strong. Or like the often repeated "I drive a big truck because it's SAFER in an accident...those little tin cans crumple like tin foil in an accident, and my big truck barely has a scratch on it!!" (or using the same argument to claim that the big ol' land yachts of the 40s-60s are safer due to being made of REAL! steel that's thicker). Take a look at accident stats some day...modern vehicles that crumple like tin foil are FAR FAR FAR FAR safer in accidents, even when you look at pre-air bag vehicles of the 90s. You're also safer in a modern tin can car than you are in a new Silverado. But I digress here, lol...
Anyways, if you have the chance, take a look at the frame under any OTR semi truck - just about every modern tractor uses a C-section frame, and you can see those frames twist up like a wet noodle when they're pulling away from a stop while heavily loaded. This flex very beneficial when under a heavy load. The boxed frames typically ARE "stronger", but they also tend to have a much narrower window of overload and failure. Meaning that if you push a C-section frame too far occasionally, it will flex more, and may permanently deform if you go too far with it, but generally won't outright fail. The "stronger" boxed frame (or one with too much additional bracing in it) is much more likely to crack/break/catastrophically fail when pushed too far. There has been a considerable amount of suspension redesigns on these modern frames to absorb more of the stress in the suspension, rather than allowing the frame flex to absorb it. Many of these are also of the hydroformed variety, which much computer analysis goes in to, rather than simply boxing in existing design C section frame rails.
Then comes what your additional bracing may do - more than likely you'll add additional stress points, where frame failure is more likely to occur under loads as it will tend to concentrate stresses at those points, rather than spreading the load across the frame. Think of how a weight distributing hitch works - spreads the load of the trailer across the entire frame to both the front and rear axles of the tow vehicle, thereby increasing the amount of towed load that the vehicle can safely handle, rather than just adding additional capacity to the rear axle via heavier springs/air bags/air shocks/etc, and increasing the lever force of the hitch pushing down against the rear suspension points.
What you really need to do is compare your 1/2 ton frame to a 1 ton frame, and mimic those differences. The biggest thing you're likely to notice is that the 1 ton frames are considerably thicker in material compared to a 1/2 & 3/4 ton frame. Something like 50% thicker. I don't recall the specific numbers right off the top of my head, but the 1/2 & 3/4 ton frames are somewhere around 1/8" thick, with the 1 tons being 3/16" thick. Doesn't seem like much, but it does make a considerable difference in strength from a load capacity standpoint. Thus, what you would be looking at doing is to plating the entire frame with additional material.
However, at least in squarebody land, there is an upside for you here. The diesel & 454 4WD Suburban frames are also the thicker 1 ton dimension, but formed to fit 'Burb bodies rather than pickup beds. This would get you the frame beef you're looking for, in an almost bolt in package. I don't recall off the top of my head if the diesel/454 4WD rear axles are on 1 ton pickup spring spacing or not. I want to say not, but don't quote me on that one, lol. The reality is that you're very unlikely to ever load up that frame to the point of failure by the amount of cargo that can fit inside a Suburban body, or the amount of weight that can be put on a bumper pull trailer...assuming you don't get dumb with it....like hitching up to a fully loaded 45K double tandem equipment trailer, lol.
FWIW, I too did some serious research in to this several years ago, as I had a super nice '06 Hemi Ram 1500 2WD, but really wanted a 3500 4WD, and had more time than money in those days. Even with what I expected to get out of my 1500 by selling it, the delta in price to a similar condition 3500 was just too much, and I figured I could just modify what I had for less money. In the end though, I ended up selling the truck, and compromised on an older F350 diesel 4x4 for the heavier hauling duties, and eventually got the K2500 diesel for the daily driver/lighter duties.
I've done my own share of suspension improvements for the purposes of hauling / towing more so I do get it. I just wanted you to know there is a certain liability. If you we not already aware.
