There are enough people here who ask about retro fitting PTT, and enough people who are buying Seariders etc where the "holy grail" is PTT on a small engine, that if it can be produced for 1/2 the price of the PT35 then I think you should find 5 customers. However would you get them to pay for an unproven design, from a previously "unknown" vendor? What happens if it develops a fault, or falls off the back and drowns an engine... ...all the more so if there is no prototype available at the time of placing the order. That said I'd certainly be interested to discuss it.
Also you're customers would be split into "clamp on" and "bolt on" engine designs. You would probably want to accommodate both.
The PT35 is probably "over specced" for what I need - I just want sensible PTT on the engine. I don't need to have a wider range of angles than any commercial engine would have had, nor do I need to raise and lower the engine height easily etc.
Not sure what you meant by "internal actuator", you've obviously looked in more detail at the mechanics than I have, but provided it works and is "safe" then I don't see a problem with it not being a PT35 clone. My only point would be it obviously needs to take more force than just lifting the engine - when driving at speed it obviously has a lot of thrust trying (in part) to push the engine "down"...