Re: bass guitar... advice...
I played bass for 20 years before playing drums. There are alot of exercises you can do to help strech you hands. One is to learn the major and minor scale and play it in every postion of the neck using one finger per fret. Or if you hands are really just tooo small you can alter your fretting hand. A lot of stand up bass players us their first and middle finger independely....... their ring finger and pinky are used toghther(ex first finger first fret : secound finger secound fret : 3rd and 4th finger on 3rd fret). You will have to slide up and down the neck more but it will work and the ring and pinky together support each other. The pinky alone on the e string can be hard to press by itself.
It sounds like you dont have alot of time to pratice. You might only want to diddle with the bass. I wouldnt give up time from drums to pratice the bass.
Its a drum and its a fish