Mod assistant 1.0.30 will work with 1.7.0 even that it will show 1.6.1
With all these changes mod assistant will install the bsipa from _local_mods\bspia.zip
If you want to (re)install bspia manually every time just skip the changes to Mods.xaml.cs

getting bsipa 3.13.7
git clone https://github.com/beat-saber-modding-group/BeatSaber-IPA-Reloaded.git --recursive
cd BeatSaber-IPA-Reloaded
git checkout 681860c90103925ac6ef06d1bfc7010beb11418a --force
git submodule update

getting latest mod assistant:
git clone https://github.com/Assistant/ModAssistant.git

File BeatSaber-IPA-Reloaded\bsinstalldir.txt
Must contain the path to the game (I usually compile on a different computer, the path can be
different, it might be that the version of the game has to be the same) with regular slashes,
ending with a slash, without new lines, encoded in UTF8 without BOM(use notepad/notepad++)
example:
G:/games/Beat Saber/


File BeatSaber-IPA-Reloaded\IPA.Injector\AntiPiracy.cs
from:
        public static bool IsInvalid(string path)
        {
to:
        public static bool IsInvalid(string path)
        {
            return false;


File BeatSaber-IPA-Reloaded\IPA.Loader\Config\SelfConfig.cs
from:
public bool Regenerate = true;
to:
public bool Regenerate = false;

from:
public bool AutoUpdate = true;
to:
public bool AutoUpdate = false;

from:
public bool AutoCheckUpdates = true;
to:
public bool AutoCheckUpdates = false;


File ModAssistant\ModAssistant\Classes\Updater.cs
from:
        public static bool CheckForUpdate()
        {
to:
        public static bool CheckForUpdate()
        {
            return false;


File ModAssistant\ModAssistant\Classes\Utils.cs
from:
        public static bool isVoid()
        {
to:
        public static bool isVoid()
        {
            return false;


File ModAssistant\ModAssistant\Pages\Mods.xaml.cs
This file contains the changes that make mod assistant install bsipa from _local_mods
from:
                if (mod.name.ToLower() == "bsipa")
                {
                    MainWindow.Instance.MainText = $"Installing {mod.name}...";
                    await Task.Run(() => InstallMod(mod, installDirectory));
to:
                if (mod.name.ToLower() == "bsipa")
                {
                    MainWindow.Instance.MainText = $"Installing {mod.name}...";
                    await Task.Run(() => InstallModLocal(mod, installDirectory));

from:
        private void InstallMod (Mod mod, string directory)
to:
        private void InstallModLocal(Mod mod, string directory)
        {
            string installDirectory = App.BeatSaberInstallDirectory;
            string localDir = Path.Combine(installDirectory, "_local_mods");
            string localZip = Path.Combine(localDir, $"{mod.name.ToLower()}.zip");

            if (!Directory.Exists(localDir) || !File.Exists(localZip))
            {
                System.Windows.MessageBox.Show($"Could not find '_local_mods\\{Path.GetFileName(localZip)}' for {mod.name}");
                return;
            }

            using (FileStream zipToOpen = new FileStream(localZip, FileMode.Open))
            {
                using (ZipArchive archive = new ZipArchive(zipToOpen, ZipArchiveMode.Update))
                {
                    foreach (ZipArchiveEntry file in archive.Entries)
                    {
                        string fileDirectory = Path.GetDirectoryName(Path.Combine(directory, file.FullName));
                        if (!Directory.Exists(fileDirectory))
                            Directory.CreateDirectory(fileDirectory);

                        if (!String.IsNullOrEmpty(file.Name))
                            file.ExtractToFile(Path.Combine(directory, file.FullName), true);
                    }
                }
            }
        }
        private void InstallMod (Mod mod, string directory)


for bsipa:
build->configuration manager: release, x64-Net4
build->clean
build->rebuild solution
compress files from BSIPA-Meta\bin\x64-Net4\Release to <game dir>\_local_mods\bsipa.zip

for mod assistant
build->configuration manager: release
build->clean
build->rebuild solution
copy ModAssistant.exe from bin\Release to <game dir>

Compile tested with visual studio 2019

IPA --launch and/or IPA "Beat Saber.exe" have to be run at some point with new .exes
I had to run the game twice to get the left side mods tab. The mod settings button was there the 1st time.

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Feel free to use my compiled one, instructions:
1 extract to game folder
2 use ModAssistant to install desired mods
3 launch game
4 if it doesn't work drop the "beat saber" executable on top of ipa
5 might need to launch the game again to get the left side mods tab
https://mega.nz/#!815gDKpK!0lymgqFf3cO5ZoiwWZA2Ut7lVa4om2wnAftrzMq9MdY