kwinnw,
Have you made a list of possible employers? Contact these organizations and ask about their pre-hire requirements, this will save you time and money. I’m not agaisnt ROV schools, in fact I’m putting together a ROV Training Vessel equipped w/work-class system, but it is possible (in the states) to land a job with just electronic/hydraulic background, local college can provide accredited document.
If you must attend a ROV school, look for one that will promote hands-on troubleshooting skills and assist in job placement; companies hire techs and train them to be pilots, not the otheway around.
Most companies will invest in the advanced training of their perosnel, and hire someone like me, whereas I bring everyone back to basics…input/output.