[Baertram]

I think he wants to swap the equipped skills, not the gear, on mounting.

Example:

Unmounted Actionbar 1: Damage1 Damage2 Stun1 Bubble1 Buff1
Unmounted Actionbar 2: Heal1 Heal2 Heal3 Heal4 Heal5

You mount your mount with actionbar 2 as active weapon bar:
Mounted Actionbar 1: Damage1 Damage2 Stun1 Bubble1 Buff1
Mounted Actionbar 2: Heal1 Heal2 Heal3 Heal4 AvaSpeedBuff

If you unmount (weapon bar 2 is still active):
Unmounted Actionbar 1: Damage1 Damage2 Stun1 Bubble1 Buff1
Unmounted Actionbar 2: Heal1 Heal2 Heal3 Heal4 Heal5

As alternative if you changed the active weapon bar if you are mounted
If you unmount (this time weapon bar 1 is active instead):
Unmounted Actionbar 1: Damage3 Damage4 Stun1 Bubble1 Buff1
Unmounted Actionbar 2: Heal1 Heal2 Heal3 Heal4 AvaSpeedBuff

This could be done by help of Wykkyd's outfitter + Wykkyd's macros (you can press a key before you mount to swap the skills) maybe, or by help of other Skill Swap addons.