Buy another goldberg and put the rcs engine in it. I fly almost all Ultimates. I only have 1 mono wing plane in my fleet. My brother just gave me a Goldberg and I am putting a ys 91 in it as we speak (already had the engine). I know what you mean abut not having a bipe I dont know what i would do with out them.
goldberg ulti
42% 3W ulti
46% h-9 ulti
50% pitts
335 sukhoi
Biplanes are the best IMO
Fred