just out of curiosity, which plugins are only VST3? I'm just curious. its only a matter of time before that will be the case increasingly due to Steinberg's draconian licensing politics.
In the meantime I highly encourage you to check out Kushview Element. For $2 you can download the latest version and use it to host VST3 plugins inside VePro.
Believe me, VSL will get VST3 support eventually, they have to because Steinberg is slowly slitting the throat of VST2 plugins everywhere...but anyway, in the meantime...so you can get your music going...check out KushView Element:
https://kushview.net/element/download/
if you're handy with a compiler you can even get the source and build it for free!! I have tested all the various sub-hosting plugins like PlogueBidule, Patchworks, DDMF, etc...and KushView element works the best inside VePro! All the other ones mentioned, all of which I own...and all of which are NOT free......have GUI related problems inside VePro for now. But I have had no problems at all with Kushview. Its quite a decent product and the main developer is also super responsive and nice guy.