Vendor note and earn-out targets

How do you set ambitious, yet realistic, EBITDA targets for vendor note and earn-out payments?

Example:
A PE buyer considers to acquire the majority stake in a privately owned company. The current minority owner who is also the CEO of the company, is expected to roll-over part of his equity in a newly created HoldCo (holding 100% of the shares in the Target company).

Historical EBITDA:
FY14: EUR 7m
FY15: EUR 7m
FY16: EUR 13m
FY17 (budget): EUR 19m

Assuming that Target EV is estimated at EUR 90m (~7 x FY16 EBITDA). This would also be the equity value assuming no initial debt.

There is a concern that the FY16 EBITDA level is not sustainable, and that EBITDA will fall back to FY14-FY15 levels. Management is confident that EBITDA is sustainable, and that the expected EBITDA uplift is EUR 6m in FY17, totaling EUR 19m.

How would you structure this deal, so that you include a safe guard against EBITDA being unsustainable (fall back to historical levels) and not being able to meet the FY17 budget?

I have an idea that the purchase price should be paid as follows:
- An up-front payment
- Vendor-note (only paid if a certain EBITDA-target is met)
- Earn-out (only paid if a certain EBITDA-target is met)

Assuming the deal can be financed with EUR 30m in bank debt.

Some thoughts on this would be highly appreciated!

Thanks in advance!