Water based ink durability on canvas
Some pigments used in inks are UV sensitive and disappear rather quickly when exposed to sunlight, others remain unaffected. Having in mind the colours you need, make some research about which pigments are used to make your desired colours and which of them are UV sensitive and which are not. 

Check what water-based products are available on the market and if you can figure out which pigments they use (they are likely to be written in their catalogue which are generally available online) go for the ones you have found out that are not UV sensitive. 

Alternatively, you can buy ground non-UV sensitive pigments and learn how to make your own watercolours (follow the health and safety instructions of the tutorials, as some of the pigments are toxic). 

Since your problem is the UV light, if you want to use varnish, etc to preserve the colours you should look for something that would acts as a UV filter (without affecting your drawing).

Also, you may want to consider using oil-based markers instead of alcohol-based ones. They may do a better job at keeping your outline drawing ink/watercolour-free.