Hi Obisteve, I did contemplate that and had AI do the calculation for me as in the pic below. 3" of fork extension would give me about a 3" trail, a little more than the desired 2 ½ " I'd like. There is a company in the US which makes extended legs in 2" and 4" , but will custom make any size. I filled out the online form for a quote and tho they say they'll post anywhere in the world, their quote form won't complete unless you enter a valid US phone number. Screw on fork extensions seem so easy, but no one appears to make them in 35mm.
I did run the front wheel up onto a 3" high block of wood tho and walked around it a couple times, then sat and contemplated it for a while, but it looked way too high in the front so will stick with plan A. At the point now of trying to muster up the courage to cut and shut the original. Can buy triple trees on eBay from the US for around $300, with almost as much again for postage, so trying to find a set here first. In any event, our clubs "Sidecar Circus", an annual event for 3 wheelers is at the end of this month so will hold off til after then, and if I haven't sourced a set by then I'll bite the bullet and use what I have.