Scope adjustment question

For Christmas I bought myself a scope upgrade for my springer. I use a Gamo Whisper Cat, and put a Gamo 3x9x40 on it.
https://www.amazon.com/Gamo-6212039X40AOCP-3-9X40-Adjustable-Objective/dp/B007VSXH36/ref=sr_1_1?s=sporting-goods&ie=UTF8&qid=1486956059&sr=1-1&keywords=gamo+3x9x40+rifle+scopes

The scope is overkill for the small range, but I need it anyways because WTFN?

As I shoot further targets the pellet strikes higher - a bulls eye at my tree 15 yards away is 2 inches high at 30 yards on my fence. Everything I shoot is within that distance band, so, 2 inches of variances is huge.

On my scope, I know where to dial the elevation to bullseye at the tree and at the fence, and I estimate range and adjust when the target is between the two.

I know the problem is the scope is angled way down at the ballistic trajectory, but I'm not really too sure there's a way around that given the short range of the shots I take.

Any tips on how I can avoid so many adjustments? (besides iron sights I mean...)