What is the highest you can trim the drives up while running above 4000 rpm, can this cause damage to your drives?

NOT very far. It's not the drive itself you need to worry about, it's the universal joints on the input shaft that will suffer. The higher you trim your drive out beyond a 'normal' drive position, the greater the angle the universal joints have to drive at. U joints don't live long at extreme angles, (more than a few degrees) and the vibration caused by the driven shaft acceleration and deceleration will tear things up. Double Cardan joints are used to minimize the effects, but they still have limits. It's the same priciple as automotive driveshaft physics, there's a LOT of engineering that goes into it........ someone correct me if I'm wrong.

Just to the end of the indicators

till the boat starts to slow down, then go down a bit....

On a fountain 3-5 is norm does depend on X dim and hull type
most all I have run are in that range.

The performance report from Fountain on my 35' Lightning stated not to exceed '5' on the drives when above 1200rpms.

Gimble Bearings aren't a cheap fix trust me. Already been there once. They got to pull the motors and drives completely out. Stay within the indicators and you'll be safe.

Motor and drive only if the Gimbal houseing is damaged just drive for a bearing swap..(Still not a cheep operation Bearing 95.00 labor 4-5 hrs

most fountains are at neutral trim when indicators are at 3.
going past 5 or 6 is not suggested for a couple of reasons. the first and important is ill handling at speeds with the possibility of shooting the bow up over big wakes, which is an issue of safety and is most important. the second is failure in the driveline. ergo u-joints, gimbal bearing's or transom assemblies if either of them go while at high r.p.m, which will cause catostrophic failure. which can also lead to safety issue's.

You better be 4 or less over 1500rpm!!!!