If you are buying a towbar mounted on have a look at maxxraxx voyager/pioneer 4 bike rack, they will carry up to 80kg which should accomadate the weight of 2 e -bikes and give you space to hang them, I have a 4 bike premier for sale in the free ads on here in excellent condition only been on the car once, if in doubt have a look on the maxxraxx website you will find a lot of useful information
Tow bar racks ;- take a look at THULE.. They manufacture a heavier gauge rack for e-bikes however we have a Thule VELO Compact which has a max load of 45kg. We use it for KTM E-Bikes with weights of around 40 kgs and have not had any issues with it.
The Westfalia bike carrier’s looked pretty good when I got to see one, at one of the shows, a bit like my Thule EuroClassic 902, they fold up and can be easily stored in the car boot when not required.