Skip, I have my battery/ignition going in in the cavity right above the landing gear. It will keep everything internal, and clean(hopefully). The CG is looking real good so far, I've had as much of it together as I possibly can, to keep check on CG, and it's looking very managable, without any additional weight. I have the tank slated to go directly over the CG, as there is tons of room there, and with a gasser you can take advantage of this. We need all the advantage we can get.
As for the mount, only time will tell. This mount is a very stout unit, and it seems to have plenty of meat to it. Like anything else though, it took a bit of patience making sure alignments were perfect. I really think if the mount breaks to the point that it's a major problem, there's alot more going on other then a broken mount. You can bet, as in all my other planes, it will get pre-flighted to the moon.
I also went with the "pitts" muffler for the BME. This required a bevel cut on the bottom of the firewall. I just angle cut a small triangle (about 3/4"to 1" or so) of the bottom/front area. Then refaced the area here, and pinned it.
This allowed me to mount engine without adding a block behind it, as you see in the link/pic above, that guy added a block behind the whole mount. I just cut away the part of firewall that didn't clear the muff.
Another advantage is it's keeping the engine/thrust washer perfectly aligned with plans, so thrustline doesn't change.
It ended up looking very clean, and the added triangulation in that area is a bonus, without ANY added weight.
It's a real nice plane, I'm really liking it, can't wait to get it done. I need patience in that area too. I haven''t wanted one done this bad in a loooonngg time. It's getting tough. Still lots of work ahead though.