Adding an extra battery

[Mr Happy]

Hi there,
I have a 2013, 16 foot, Sport, Bambi...
I am wanting to change my onboard battery from one battery to two and looking to go with AGM. When I add an additional battery will I need to change anything else in the electrical system? Will it affect my solar panel in any way?
Also, I want to add a brighter light next to the door, on the Bambi there is just a very small step light and I was wondering if I could add a brighter light at eye level and run it off the same switch?
Thanks very much!

[BambiTex]

As long as you have space, wiring up 2 AGM's in place of your stock battery should not require any other mods. Do you have a good (multi stage) converter? If not, you should get one regardless.
Change out the bulb for a bright LED and you will get more light with lover current draw. No other changes required.