I have a little 15w module to keep my coach batteries topped off in my Transit(not Connect). Because they're Gel, I run the module through a charge controller to make sure I don't send too high of voltage and prematurely age the batteries.
For anyone thinking of adding a solar trickle charger to their Mav, I highly recommend getting a $10-20 charge controller to protect their battery from too high voltage or over-charging; as it will cut off power when max voltage is reached.