I realise this is on the last page and may help no one but if you wish to continue to play KSP using all your mods that are only compatible with KSP 1.3.0 and you're using steam, follow these instructions.
1. Right-click Kerbal Space Program in your games list.
2. Click Properties.
3. Click BETAS.
4. Select from the drop down menu "previous_1.3.0 - 1.3.0 Kerbal Space Program"
It will regress to 1.3.0 which I believe is roughly a 40MB download.
5. ???
6. Profit
The game will be playable with all your mods like there was never an update.