Autocross or in SCCA-land "Solo". Cone dodging.

I read through the 2012 SCCA Solo rulebook and it looks like E Modified would be the best fit for classing for the 818. The Modified section (Page 140) specifically allows Kit Cars.

18.1 MODIFIED PRODUCTION-BASED CARS
A. Eligibility
Classes DM and EM contain production-based cars which are per-
mitted additional modifications beyond those allowed in Prepared
classes CP through GP. Models must meet the requirements of Sec-
tion 13 (first paragraph), be specifically listed in Appendix A, meet the
specifications below, or be otherwise recognized by the SEB.
1. Kit Cars
Kit cars, which were originally designed, constructed, and licens-
able for street use, may participate in DM and EM if they are ap-
proved by the SEB. Members desiring approval of a particular kit
car should provide the SEB with detailed information regarding
the kit model and contact info, if available, for the OE manufactur-
er. For obsolete kit cars, the member will be expected to provide
construction specifications, dimensions, and photographs for the
SEB to examine and keep on file. The SCCAŽ will evaluate each
submitted kit model individually, and the evaluation will ensure
that the specific model:
a. Follows current DM and EM allowances regarding minimum
floor pan dimensions (see 18.1.B.1.j).
b. Has no unusually advantageous aerodynamic features.
c. Has no exceptionally low center of gravity.
d. Has no exceptionally high strength to weight ratio.
e. Has no other unique features that would upset the competitive
balance in DM and EM.
f. Has independently-verifiable evidence of at least 10 examples
which meet the approved specification produced. Extremely
limited production sports racer-type efforts are discouraged.
Constructed examples of approved kits are subject to the follow-
ing:
a. They will automatically take the Modified Tub weight penalty
(see Appendix A).
b. They will have the same weight/displacement scales and
weight bias penalties as production-based cars.
c. They will be allowed all the modifications that production-
based cars are permitted,
d. They are subject to the same engine/transmission restrictions
as production-based cars.
e. They must meet the same safety requirements as production-
based cars.
The Minimum Weight for EM for an engine displacing < 3200 cc Naturally Aspirated. or <2,285.7 cc Forced Induction (2285.7*1.4=3199) is 1750lb. That's 1700 lb plus the Modified Tub addition of 50lb. I assumed anyone that prepared their chassis for EM wouldn't take the 50lb reduction in minimum weight by having the RWD wheels have <51% of the total vehicle weight on them and would opt for 40%/60% distribution.

All listed weights are with driver except where noted otherwise.
Weight (with driver)
Page 229 and 231 respectively.

I think the only thing standing in your way would be Jeff Kiesel in his 1801 lb Turbo Rotary Powered Monster

Car was running E85 with mid boost and making around 350hp to the wheels and weighs 1810 with driver. He runs Goodyear Formula Atlantic R160 tires.....