From version 1.20.06 Mainline you can use single partition templates, Essentially just one large / partition and no swap.
To do this you must set both the disk to resize and swap partition fields to 1 (or the correct partition number) when adding the template.
We have supplied a few single partition templates in our template repository https://templates.solusvm.com/kvm/single_partition
The default generated swapfile size is 256MB, if you want to change this you can edit the first-boot.sh script located in /root/scripts/ within the template as well as include any other first boot actions you may want to add. The following article describes step-by-step instructions how to do this.