How to run multiple Rack::Handler::WEBrick in one Sinatra/Grape file

Question

Basically I have multiple API applications in one Sinatra / GrapeAPI file

require 'sinatra'
require 'grape'
require 'webrick'
require 'webrick/https'
require 'openssl'

CERT_PATH = '/opt/myCA/server/'

class WebApp  < Sinatra::Base
  post '/' do
    "Hellow, world!"
  end            
end

class Api1  < Grape::API
  get '/test1' do
     {xyz: 'test1' }
  end            
end

class Api2  < Grape::API
  get '/test2' do
    {xyz: 'test2' }
  end          
end

webrick_options1 = {
        :Port               => 8443,
        :Logger             => WEBrick::Log::new($stderr, WEBrick::Log::DEBUG),
        :DocumentRoot       => "/ruby/htdocs",
        :SSLEnable          => true,
        :SSLVerifyClient    => OpenSSL::SSL::VERIFY_NONE,
        :SSLCertificate     => OpenSSL::X509::Certificate.new(  File.open(File.join(CERT_PATH, "my-server.crt")).read),
        :SSLPrivateKey      => OpenSSL::PKey::RSA.new(          File.open(File.join(CERT_PATH, "my-server.key")).read),
        :SSLCertName        => [ [ "CN",WEBrick::Utils::getservername ] ]
}
webrick_options2 = {...}

Rack::Handler::WEBrick.run Api1, webrick_options1 # this will work
Rack::Handler::WEBrick.run Api2, webrick_options2 # but when I try another one, 
                                                 # the other will not 

Grape gem is recommending to use cascade:

run Rack::Cascade.new [Api1, Api2, WebApp]

However this will ignore my precious SSL settings.

How can I run multiple server configurations?