The first thing I would do is replace your 90 ° bend with a 90° T and put a roding point on it where your old gully is laying.
As dropping waste from height may not clear the bend.
I brought this little 1.5T machine for sorting out the plot initially.
As we now have planning Im looking at buying a JCB 3X or similar as they are much more practical as the build moves forward for shifting materials.
This is speaking from my past experience of self building.
At the end of the build I will of course need another small 360 for the final landscape bit's, that I will buy in again.
It's a cheaper way of doing it than hiring in.
I'm not sure how spending more capital on a more expensive digger alleviates you from the risk of repairs.
All things mechanical go on the blink when they feel like it.
The rates for ground workers with machine's has plummeted as the the world and his dog now own them. They've got the kit on fiance and are struggling to make it all pay.
Our local plant hire companies buy in new machine's run them into the ground until the warranty expires and then sell them off. Repeat.
Try machinerytrader.co.uk the dealer's on there are ligit.
Lower your bucket to the finished height your trying to achieve, then track backwards with the machine
or
lower the blade to finished height, swivel the cab round by 90° so your looking directly down on the blade, then track forwards
or
buy or make a grading beam
Concrete posts and gravel boards can be a pain at the best of times.
Personally I'd do as the contractor said... bark and top soil to fill in the gaps.
If you start digging out to drop the gravel boards you could end up with a fence top that is out of line in-between bays.
Did your delightful neighbour share the cost?????🤩
We've got trade accounts at 3 builders merchants.
I do a bulk list of items required for each stage and present it to the B.M's and see who comes out cheapest.
The only items that stay constant is red building sand and the brand of cement so the muck is the same colour throughout the build.