I have the Crank-2's and these days I rarely use them, but I know what you're talking about because I built myself through various ADJ parts(special orders to get what I needed) a 15-foot Crank-2 truss system using ADJ I-beam trussing and it works fantastic.
Now, I also have 4 LTS-2 stands, 1 of which I have yet to open, but that's irrelevant. I haven't taken the T-bar out and put it on an Crank-2 stand. I know that if I compare with my On Stage Stands 10-foot truss, the parts that would go on the crank-stands are slightly too big, as the Crank-2 is 1.5" and the up on the On State Stands tube is 1 5/8". I do know I have sufficient spare parts where if I had to replace the connector on the T-Bar to fit the Crank-2, I could if I had to do it.
I have to think back to what I did a while ago because I ordered 2 or 4 T-Bars from ADJ. 2 of the T-Bars I used were for 8-each Par 38's(4 top, 4 bottom), and these were the T-Bars for the On Stage Stands trussing sytem. I then repeated that with T-Bars bought from ADJ and I think I adapted them for use with the Crank-2's. Like the OSS T-Bars, they were for 8 Par 38's(4 top, 4 bottom).
As far as the T-Bars I use routinely with the LT-2's, those hold 4 ADJ 64 LED Pros each(2 stands), and they feel durable and are 1.5" in diameter,which works with the 1.5" o-clamps, but I've chosen to bolt these down.
I would say that using these T-Bars for the LTS-2, you'd have little to NO problem hanging 30 pounds of lights off these, provided you make a real effort to evenly load the T-Bar.
Will common clamps fit it? I can't see any valid reason why common clamps wouldn't fit it. I mean, it's a 1.5" diameter pole, so that should work fine with just about any clamp on the market, including most C-clamps and S-clamps. I like the o-clamps because they are non-marking due to their rubberized inner sleeve though.
Your idea of a moving spot and a moving wash on each side? Well, that sounds like you'd evenly load the T-Bar, so I think that you should be OK. I would just run the legs as wide as possible on the tripod for maximum stability, and put the 2 legs BACK and 1 leg FRONT, and the T-Bar has the movers on the "front side" more or less, for maximum stability. It also depends on how you're planning to mount the lights, but overall you should be good. I can argue for a hang from the bottom or a hand pointing out, but I'll let you deal with that. You'll definately want to utilize the included support arms with the T-bar for added stability.
ALSO, you can use the T-Bars WITH the trussing, provided you leave yourself some space.
But as far as actual capacity, I'd say, either check out the LTS-2 page or call support. That's your best bet.