I was successfully able to run Seaside on the minimal Pharo 7.0. After the release cleanup the resultant image has about 12.4 MiB.
The loading script expects that in the working directory you have the Pharo repository clone (in a floder named ‘pharo’). You should modify the loading script to point to your real Pharo repository clone. This clone is needed to load SUnit into the minimal image. You should have PharoV60.sources reachable from the image.
The Seaside is loaded from my fork (github://pavel-krivanek/Seaside:minimalPharo/repository). I had to create a modified version because the original baseline broke the ZincHTTPComponents.
The strange line:
Smalltalk vm parameterAt: 25 put: (Smalltalk vm parameterAt: 25) * 50.
…sets the garbage collector. Without this the Seaside loading can fail on insufficient object memory.
wget -O – http://get.pharo.org/70-minimal | bash
pharo Pharo.image loadSeaside.st –save –quit
pharo Pharo.image startSeaside.st –no-quit
Starting of the image takes about 0.1 s on my machine.