ᐅ Challenging zoning plan

Hi,
We have the following issue. My wife and I would like to move back to my hometown and build a single-family house on a suitable plot.
We would need 1 master bedroom, 2 children’s rooms, 1 office that can be used as a children’s room if necessary, an open plan kitchen combined with dining and living areas (like our current apartment, which we love), a basement for building services and storage, a guest shower toilet, and a family bathroom.
There is a new development area, but prices there have skyrocketed. The plots are on average 400 sqm (4300 sq ft), which is too small for our taste since it means you can practically see the neighbor’s plate, and the lots were allocated by lottery among interested buyers. However, this area has a fairly flexible development plan allowing almost all residential styles (gable, shed, hip roofs, townhouses, no fixed knee wall height). I found a few vacant plots at the edge of this development and one ideal plot measuring 23 x 30 = 690 sqm (7,600 sq ft) with a southwest orientation. But here the over 30-year-old zoning plan applies, containing the following design regulations:
- WA I (residential area)
- Floor area ratio (FAR) 0.4
- Plot ratio 0.5
- Roof pitch 35°–48°
- ED (unspecified abbreviation, presumably related to energy or design standards)
- Knee walls (dormer walls) higher than 0.80 m (2.6 ft) measured as the vertical distance along the outer walls from the top of the raw concrete floor slab above the ground floor up to the top of the rafters are not allowed
- The base height (top of ground floor finished floor) of newly built houses may on average not exceed 0.80 m (2.6 ft) above the level of the adjacent road surface. The elevation of the traffic areas shown in the zoning plan applies for their grading.
- The roof pitch specified in the plan must be observed with a tolerance of plus or minus 5°, unless otherwise indicated
- Subordinate accessory structures and setback garages are exempt from the roof pitch regulations.

To me, this reads as if there’s hardly any freedom in design. The biggest issue is the knee wall limit of 0.80 m. I do not necessarily want a townhouse style and don’t mind a gable roof, but if so, with at least a 1.30 m (4.3 ft) knee wall. I used to have my bed under a sloped ceiling as a child and frequently hit my head. My first apartment was also in the attic, and it was very difficult to find furniture because almost every corner was sloped. Plus, it got extremely hot in summer. The only solution I see here is:
- Build 0.5 m (1.6 ft) thick knee walls to reach a 1.30 m (4.3 ft) knee wall height (at 45° roof pitch). This would reduce living space by about 8 sqm (86 sq ft) for an 8 x 8 m (26 x 26 ft) house but at least avoid dead corners.
- Plan dormers (I have not found information if these are allowed to have flat roofs)
- Master area downstairs with bedroom, dressing room, and shower toilet, and use the entire first floor for the children.

Am I allowed to have a staggered gable or a shed roof?

Am I allowed to have flat roof additions? My uncle faced very strict building regulations and solved this by building an 8 x 8 m (26 x 26 ft) house with a 45° gable roof but adding a 3 x 4 m (10 x 13 ft) flat roof bay window for the kitchen on the west side and a 3 x 5 m (10 x 16 ft) flat roof bay for extra living space on the south side. Would my zoning plan allow something like that?
Does anyone have a similar zoning plan and has made clever use of it?