On the Axis it's a pain, but it can be done from the front. I'm not sure for the Vegas. I was able to loosen the battery clamps with a one-handed gymnastics/stretching routine. Then I was able to pull the cable ends far enough forward to install a disconnect switch.
I'll do the same to attach permanent leads for the cool new solar charger my wife bought me for Christmas.
Access is easier if you remove the two fresh air ducts and tuck them back out of the way. Don't forget to replace them when done.
Let us know if this works on the Vegas.