Can't really comment the SLSA Mal, but getting out in the water even if your just swimming is going to help with paddle fitness for sure. I have a SUP for knee & below, a longboard for knee to waist & a few shortboards for over waist

Unfortunately I don't always have time to get out in the water as much as I'd like either

If your asking on advice about these things, your probably better off hopping over to the longboarding room. Personally I think if your gonna be longboarding, you may as well have something thats an allrounder.