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I, for one, would never manufacture an ultralight that didn't meet the letter of the law  especially one RTF.
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First show me a good performing FAR103 ultralight aircraft using these proposed layouts, that comes in significantly lighter than the weight limit to allow for dual mode items, and then maybe I'll get onboard with the goal.
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You do not need to meet FAR 103 but it is a big plus if you do. If the manufacturer meets the requirements on a mass produced RTF and the user modifies it then the user needs to do the required paperwork (certification of aircraft and operator). If ithe modification becomes popular and the manufacturer does not incorporate the changes the after market will step up to the plate.
You can do the experimental LSA with a RTF aircraft. Don't get paranoid over the UL103 versus LSA. Design what works then work the design (do the paperwork).
Referance: Northwing ATF and similar light trikes.
This is a starting point. You can add weight (64 pounds) and speed (20 mph) and performance (shorter landing distances, 1/2 or less look at HG [Hang Glider] landings versus trike landings). There is considerable growth potential. Much more than working from the top down as in taking weight out of an airplane. Begin by removing the fuselage from your design and how much weight do you save?
Add aerodynamic pitch control to the trike and incorporate a higher performance and lighter weight wing with folding and geometric/aerodynamic roll control.
You do need to inovate not just copy and add off the shelf components together for the final package. The rolling gear is the big elephant in the room here as indicated in prior posts.
Wing folding and control systems may be the baby elephant.
ATF Trike · Specifications
 
Weight
 102 lbs.

Empty Weight
 186 lbs.

Gross Weight
 550 lbs.

Climb Rate
 Approx. 300500 FPM

Sink Rate
 220 FPM

Glide Ratio (L/D)
 10.5 : 1

Wheel Base
 W62" (outside)

Wheel Base
 L61" (fronttorear)

Height  Trike folded
 2.25 feet w/o prop

Smallest Size folded
 W27" x H30" x L55"

The Solairus light trike wing is available in two sizes:
Sail Area
  17M
  16M

Span
  34.7 feet
  32.5 feet

Nose Angle
  126 degrees
  126 degrees

Aspect Ratio
  6.33
  6.15

Stall at Gross
  21 mph
  21 mph

Trim Speed
  2530 mph
  2530 mph

Top Speed
  45 mph
  45 mph

VNE
  53 mph
  53 mph

Sink Rate
  220 FPM
  220 FPM

Glide Ratio (L/D)
    
with Solairus trike
  11.5 : 1
  11.5 : 1

Glide Ratio (L/D)
    
with ATF trike
  10.5 : 1
  10.5 : 1

    
17M = 390 lbs to 490 lbs Gross
(Approximate Pilot weight: 180 to 290 lbs.)
    
    
16M = 320 lbs to 420 lbs Gross
(Approximate Pilot weight: 110 to 220 lbs.)
    