Yep, chop away. Many of us have done just that and trimmed that forward skin back to clear. The fiberglass strip will cover that area later on when you finish up the canopy. As for how close to match the roll bar to slider frame? A range of alignments will work out just fine. I've seen them very tight on some planes, on mine it worked out a bit farther apart and it worked just fine. I have about 1/2 inch between the bars (which is about the outer limit I think) I did need to support the glass / carbon when laying it over the top so as not to sag down into that gap, but once the strip is in place it's all sealed up nicely. Just work on getting the frame to slide in place nicely and the latch to operate correctly and you should be good to go.