Sounds like you'd need a $500 rim for it to me.
There IS a point, where cheap bike parts fail. Not saying a $5000 DH bike cant hang. But you are looking at a cheap deal on a motor, when what you are planning will need a $2000 fork on it.
More affordable stuff can still be fun, and relatively safe, with 3000w or so, and pull a wheelie when you want one.
The worst e bike I ever rode, for me, was a 10,000w wheelie machine. To some it would be the best, but for me, I just kept having to jam that front wheel back down to turn it. It just would not stay down unless you only gave it 3000w. Out in the dirt, I easily left it in the dust riding a 1000w bike. I could turn mine, and the trail was lots of turning.
Fun on the street though, where you could just wheelie for a block.
The cheaper motor out there is the muxus, but it is too wide for 135 mm, so your bike better be adaptable to wider somehow.