Need help on idea_diodes/switch/speakers

I am currenly doing a new install and was thinking of an idea.  I have 2 10" subs in boxes in my trunk run by a mono amp on a shelf I built above the sub boxes...also on the same 'shelf' is a 4-ch amp for my inside speakers, a capacitor, and a fused distro block.  This shelf takes up almost no room b/c it is on top of the sub boxes.  To save space at times when I need it...I can take out my boxes and the shelf in a matter of minutes, but this leaves me with no sound( due to the 4-ch being removed.)

My idea:

To rig up switches between my HU and the speakers so that I can turn on the speakers by using the HU's internal amp...I was also thinking that I would need to place diodes inline between the switch and the speaker so that when my 4-ch is on no current will be going backwards to my switch.  Will this work?  Is it a good idea?

Some questions?

Do diodes have a resistance?  Will it be too much for what I want to do?

Will I need diodes on both the + and - leads?

Should I switch the - leads as well as the + leads?

Any help/suggestions/ideas are greatly appreciated

Thanks,

Matt