The very Tip should be the same diameter, then the Tapering Bug Body would be widest in the middle, then tapering back down to the "original" diameter at the start of the tail. Flipster-style body proportions, Flipster-style "ridges" (or just the Original RT ridges), with the Flister-style "indentation" down the center, lengthwise...and try to keep the Thickness of this Widened Body the same, or close to the same, as the Original 7" RT's Thickness (at the thickest), while the Flipster-style indentation down the center may be thinner than the Original 7" RT thickness. Me personally, I'd make this wider body positioned so the tail is "up" or "down" naturally, not "to the side"...the greatest width would be "90 degrees" to the tail.
Would the new width be 150% (1.5 times...or added 50%) original width or 200% (twice) original width?
I like the idea. Your idea here, would also open up the door if someone wanted to throw that bait as a Snake, because the wider body would ride higher, easier.
Edit: AHA! You said doubled. Roger on'na 200%.