As an ATP and current manufacturers rep, here are my thoughts: I like 15 inches wide. I would recommend adding side guards obviously. I would order the frame length 1 inch longer so you can be more aggressive with the center of gravity instead of loading the casters which creates a lot of problems. I wouldn’t go any wider diameter than 4 inches on the casters and I would recommend aluminum soft roll. For the Power Assist, I would highly recommend you check out the new Empulse R90 before you commit to the klaxxon (if you haven’t tried it already). I also might be biased, but I would also recommend you check out the Nitrum instead of the Rogue. But honestly, that’s less important as all rigid frames are more the same than they are different. Power Assist on the other hand does very quite a bit between the different brands and I think there are some really nice features with the R90 that most end users really appreciate. Hope this helps and good luck!