Well it sounds like you're doing this more for the fun of it, than trying to make the airplane something that it's not.

It sounds like weight is under control. I didn't get a chance to weigh my first Partner before I started converting it over to electric, but the second one is heavier and with a YS 1.70 it weighs around 10 lb 6 oz, give or take. I also won't be getting a fair comparison, as I am building new wings and stabs, that should be 5-6 ounces lighter than the original panels, as well as recovering the rudder to shed some weight, as it was covered in Ultracote and then painted over with Chromabase and then cleared. Just the covering/paint weighed 1.5 oz, half of the weight of the rudder itself! I would think that if I didn't do these things to shed weight, it would end up being a wash in the end with my setup (Plettenberg 30-10 Evo, Schulze 32.80KA, and Thunder Power 5300 ProLites).

If you're looking into the Hacker, I would gut the original firewall, and mount the motor with the rear essentially in a nose ring, that has two triangle gussets to attach to that would allow you to adjust the thrust in the rear. The front would be hard mounted as well, and would likely replace your nose ring mount you have in place already. If I were to convert the airplane over, this would be my preferred setup.

I wouldn't fool with making it a top access airplane if I were you. You'd have to be very careful with your cutting, and then have to add bracing for both the fuse and canopy. I would think that if you removed all of your internal components for glow, you'd end up with the same access on the bottom as you would cutting a top access in, unless you made it very long like some of the purpose-built electric two meter designs. I would replace it with a flat plate that has two dowels in the front, and a hatch latch in the back, that way you could get inside quickly. This would probably be the easiest solution, and you wouldn't have to worry about messing up your paint.

Now that I've heard some feedback from you, the purpose of this project that I got from the first post has changed. It sounds like it could be pretty neat!

If you go through with it, post photos!