does anyone body triangle in guard while going for a guilotine?

I see a lot of MMA fighters use the body triangle from guard but I am yet to see anything truly effective get done from there.

I think it's a horrible idea. It won't help the precision of your finishing technique, and it completely takes away your ability to control the distance. If you go with another form of lower body control, like your shin across their waist and other leg over their back, then you can do things like base out to the front headlock if the choke doesn't work. Or follow them to the mount if they try to roll out. The most "leg wrapping" style guillotine that you really see anymore is the straight up closed guard during an arm-in guillotine.

The only effective finish from the body triangle from guard is the kimura. Imo.
See Javare vs Matcelo.