Double major is overkill IMHO, but it may work for you.
Since your interest is "mecha - tronics" you need to determine the blend that suits your desires (time, effort, money, knowledge, training). For example, 50/50 ME/EE, or 60/40 ME/EE or 40/60 ME/EE, or what ever.
Example: I'm a BSME + Master's in Manufacturing Engineering (emphasis on automation). Worked in manufacturing automation, controls, and robotics for 30 years. I took some EE courses to augment my knowledge base, and learned by doing all the other stuff I wanted to know and needed for my various jobs. Now I teach at the university level. This past couple weeks I have been designing & building electrical & pneumatic control system panels for my lab's industrial robot stations. For which I also designed & fabricated all the stations, EOATs, mechanical components, too. And constructed the course to teach industrial robot fundamentals, math analysis, programming, workcell design, and constructed a series of homeworks & lab assignments.