Risks of Running High Amp Alternator?

IMHO

I would take all those electrical loads and run them to a dedicated distribution / fuse block directly off the battery. then run whatever Alternator you want with the output of the Alt going directly to the battery / distribution / fuse block. the rest of the car, under dash, lights etc can run off of the battery / alternator as it does now.

let's say the car without all the extra electrical loads pulls 10-20 amps with headlights, brake lights etc on. and your add on electronics draws 100 Amps. your 150A alternator can supply all of it and charge the battery too. If on the other hand you tap all the extra electronics onto the existing wiring in the car your set to roast marshmallows