Nice job on the project!
I've used the heat method to bend PVC for intakes on canister filters and just packed the PVC pipe with sand to avoid the 'ripples' or deformation of the PVC pipe and it worked great.
I've also heard of people using flour or granulated sugar packed inside the PVC to help hold the shape. Just tape the open end of the pipe closest to the end of the bend.
Eheim Pimpette #270
Eheim Pro II 2028; Classics Series -2215, 2217, 2260, 2262; Pro 2229 Wet/Dry