I did it briefly with a former T, but then I moved. I only managed 2 sessions, and it was incredibly taxing. It was VERY worth it for me though. If given the opportunity, I would try it again.
My T did sit closer than normal, but not overly so. I think I would have had some trust issues around doing it with a T I did not know, but if done correctly (building up the safe space before working on the trauma), then I see no issue doing it with someone else. My T and I had done all the prep work for it from the time I started seeing her not so much in prep for EMDR, but to be able to get me into a safe emotional space easier than I had been doing.
I hope you have luck with it. I know it isn't as effective for everyone, but I found it very helpful for the few things I was able to work on. (as a practice, we worked on my fear of spiders, and since the EMDR, my visceral reaction to them has decesed significantly. I ws already able to help scoot them outside, but now I am able to do so with a lot less anxiety even if they are freaked out themselves and moving around really quickly).
Oh, my EMDR sessions with my T were always 2 hours because we found I needed time to safely ground after them. It would take me quite a while to be able to get into the groove of the session, and I needed the extra time to finish the part I was working on that day, then be able to settle myself afterwards. It may no be that way for everyone, but it's what worked for me.