With a fisheye lens you are looking at shooting distances of less than one foot from the dome. If you go further away and there are particles you have a good chance of having lots of backscatter on the edges of the picture even with the strobes pointing forward unless you have very very long arms
That's basically what I was afraid of.
I've been using the 8/3.5 almost exclusively since I bought it, but I guess I'll just have to go back to using the 9-18 when the viz really sucks and I want WA instead of CFWA and semi-CFWA. 8+8" arms are out of the question; the main reason I chose a micro four thirds system was because it's noticeably more compact than a dSLR system.