Struggling to keep the template line and apex true

Guys, I struggle to keep the railline true to what i’ve drawn i keep oversanding and messing it up and i end up going narrower in the end.
I take my time and measure everything, i cut it with a jigsaw close to the line then i use the styrofoam tool to get to the line and then i try to make the rails perpendicular to the board with a hardpad and sandpaper, as i dont have a rasp for that i keep messing it up and have it wavy and spend a lot of time on this task.
Any ideas on how to do better and maybe do a diy tool for that?
I wanna get the railrunner tool from greenlightsurfsupply but they dont ship to my country…

I use a “Fence Post Level,” and variants of the concept, to true blank outlines to perpendicular and smooth outline curve lines. I like to leave close to a 1/8” foam buffer outside the template trace line for grinding down “slowly” with long, smooth, full-length strokes.
Pulling toward you makes cleaner/smoother full-length sweeps (but I have pushed when “impatient.”)

Found original McDing Post link from my previous post.
BTW practice cutting out template outlines and smoothing and truing outline curves with an inexpensive piece of XPS housing insulation (DuPont or Owen’s-Corning).

I cut Eps from block, so not sure if this is helpful.
After hotwiring from the block I spend some time getting the bottom leveled out. Look for " Bruce Jones in the shaping bay" on you tube. Best video.

Then I cut with a hotwiretool that has a 90 degree angle to it along the template. This leaves a tiny margin to the pencil line.

I then mount a 90 deg guide on my standard cheapo planer and run along the rail line with the depth adjusted to ZERO . On the curve it will cut a tiny bit.
From here on I don’t care about the pencil line anymore. The planer will show what you have to do to get it right.
Judge for yourself how far you want to go into nose and tail , if it is too curvy the process gets sketchy.

Some guys route the outline , i think it’s displayed in the video too, but that obviously only works with a very precise template.

From here on you don’t touch the apex anymore till the very end.

Hope that helps a bit,

just hold your planer horizontally and take a few small passes walking down the blank. trust yourselg getting to your makk. smooth it out with 80 grit on your sanding block.

yourself (yourselg) mark (makk)