Hi Mullet and welcome.
I am buliding the Rogue Runner in the 20' extended version. I have the Mercury 115 outboard already, but am glad I waited finalizing my plans. I was also looking into powering it with a 1200cc size jet ski pump. That project is on hold while I finish building my shop to build the boat in.
I picked up a 20' aluminum sled for $700 and have the same options as the RR. BUT! I foumd surface drives and am going to explore them fully. I need shallow water running too. But jets dont like weeds, sand or gravel. I dont have Manatees, but plenty of submerged obstacles. Im going with a DIY (plans from an NA) version that rides at normal depth, but will lift/ride up in shallows. The prop should be protected for marine safety too I think. Cutting prototype parts now.
Good luck and have fun!
Chris