After the microlite example, I also mentioned gliders such as the type I flew (Ka6) for 23 years, of which there are probably a hundred similar examples in the country, where in spite of stretching the maximum cockpit load by the maximum permitted 10 percent, I found myself unable to accommodate anything extra at all within the permitted weight limits. No room for extra instruments on the panel, no accommodation for extra weight for the battery to drive them. One did not have to be particularly heavy for the situation to arise with older gliders of that type, and possibly numerous others.
(The batteries required to drive a transponder, for several hours flying, would weigh several kilograms, in addition to the weight of the unit itself.)
The CAA response was that they didn't mention practicalities as a problem that emerged in their consultation, because it was covered by ”cost.” Their argument was that anything can be solved by throwing enough money at it. In cases like this, however, the only way throwing money at the problem could solve it would be by throwing away the whole aircraft and buying a different one, without such as severe weight limitation. In the microlite case, I wonder if that might extend to throwing away existing licensing and paying for a new course of training to get a licence for a different sort of aircraft.
Chris N