I own no land so take my words with a grain of salt but before putting time into doing something, I'd make sure it would 'pay off'. There are always bottlenecks whenever you have a multi-step process, so step 0 would be identify the bottlenecks, since an improvement there would help the whole process more. If you're just looking to cut down the time taken, then rather than mount a blade in front, mayble look at mounting it double wide. I would think any balancing issues would be worse if mounted front and back, downsides, it might not mow the area under/between the mowers. When I search double bar mowers, that seems to be one of the more popular configurations. Other option would be to cut on the same side, but somehow trail the second mower behind and offset it ~7' so they don't cover the same area. Looks to me the 'Rouse' double bar mower works like that.
For the rake, the missed hay might become a bigger issue if you run two smaller ones versus one larger rake, but thats nothing more than a gut feeling
If you're thinking of doing motor mounting, I'd suggest to check out old Horse Progress Days videos or similar. different situations, but those that work with horses often mount motors to their machinery or forecarts to power them. From what I remember from going ~5 years ago, they look more at the torque than the horsepower of the engine.
Looking at the 8n, it seems pretty small (~22hp). What baler do you run with it?