I would strongly advise you to stay away from the Yelvington or Trinity trike kits. I was under contract with Trinity Trikes after they bought out Yelvington and worked at their Largo Florida facility for a year to attempt to help design/revise/improve the original design which had lots of issues. I also was tasked with taking all sales calls and fulfilling the few orders that eventually shipped as well as after sales follow up and I can tell you with certainty, the the majority of the new kits sold had issues.
Richard Yelvington was retained by Trinity and was still in charge of final design and unfortunately was not keen on taking advice from myself and the very competent new engineer/designer, so problems persisted and the company never really got off the ground. There are no spare parts available, so you would be on your own to maintain it.