John,
Unfortunately, I can't say I've used that style tank on a half-A. So I am quite curious about your results if you go that way. Please share your results.
A friend used to use that style all the time on his .35-sized sport planes. But that was a long, long time ago and if the plane fired up and went in circles we were happy....
I think the tank height may give you some draw problems; or, said perhaps more accurately, the fuel pressure head will change quite a bit during the run. That design of tank minimizes the problem of needle valve location by skinnying up the tank in the lateral direction (good) but pays a price for the larger fuel load by exaggerating the height.
I fiddled with a number of tanks on a Junior Flight Streak. As you might expect (according to a corollary of Murphy's Law), a conventional tank of very limited capacity ran beautifully thru the whole tank. I tried several others, including a custom tank to compromise between the excessive dimensions (run variations) and a decent run time with little success. I will say that my next variation was going to be an inboard tank, but didn't have a small enough one handy, so the plane went back on the wall. But the inboard tank is an option you might consider.
Dave