Looks quite feasible. There are a few mid drive motors. I've installed two TSDZ2 kits and two Bafang BBS02 kits, The install is easy. I've mounted batteries on the downtube or put them on rear racks,
The TSDZ2's are torque sensor and lower power.There is a higher power version called the TSDZ8, but it's a few pounds heavier. The BBS02 are cadence sensor and high power. Also a lower power BBS01. I suggest you read up about torque and cadence assist. Other motors include the DM01 and DM02.
Batteries can be 36 or 48 volts. I prefer the latter. The capacity is defined by the Ah. Higher Ah means a bigger battery,
It's going to cost at least $800 for a motor kit and battery, You can buy a 40 lb Aventon hub motor bike with a torque sensor for $999. There are also mid motor bikes for not much more.
Make vs Buy is pretty much a Buy for most people. I like doing the Make because it allows me to motorize some old bikes for sentimental value. I already have some batteries I can move around. so each new iteration only costs me $300-450 for a motor,
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