I just use a JBL Charge 3 with a little velcro on the base so it sticks to my carpet and docent roll around. No holes in the dash or speaker holes. No wiring either. I take it with me to play elsewhere as well. I normally use my iPhone on Pandora fo my music. A sound system just doesn't do well in my car because of all the other noise around but this little device does pretty well. This is just another suggestion/alternative for you.
Lastly, The thing will also charge my phone. ............Bruce