I used and will illustrate something similar to The Steve Sinner double welded 1.25" boring bars. I have posted in the past about my boring bar journey. Please read this previous post as there may be some useful info for you.
I have the Hope hollowing system. I have the 3/4" bars straight and bent that are great. I can use carbide or HSS scrapers. I also have the Hope 5/8" bar that only uses the carbide cutters. These cutters seem very aggressive, most likely caused by my inexperience. The carbide cutters are...
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The advantage of the Sinner bar is that two bars are much stronger than 1 bar and for the same length you have increased your hollowing depth capabilities. A bonus is the double bar acts as a torque arrestor while being held in Sinner's dual bar trap. I borrowed this idea in my own home grown custom boring bar system. If you view the last photo in the post above or the first one below in this post, you will see that the 1.5" boring bars from Clark system are connected to a Jamison-like d-bar trap. (There is a 3/4" interface on all Clarks bars allowing me to connect it to the bar. Sinner's tool interface is 5/8). My D bar's sole purpose was to add stability but it was hitting the back wall from the lathe with deeper turnings and taking away from using a longer Clark 1.5" bars. (see last photo in the link above). To solve this I used Sinner's Idea but I didn't weld two bars directly together. I had a few pairs of 1.5-inch motor shaft collars welded together and I connect the bars with their set screws. Here are some photos illustrating this. I have enhanced the trap by reinforcing it with a straight bar, bigger screws, and beefer springs in the second photo below.
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This photo shows my how my laser assembly is attached to the boring bar.
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Hope this gives you some alternatives.