[nullve]

Idea: Build a system around a strong but limited 1♦ opening showing

* if unBAL, something like the bottom half of the top half of a standard 1x opening range, and
* if BAL, a hand too strong/weak for 1N/2N, respectively

.

Example system

P/2♣+ = standard
1♣ = standard rule of 19-ish 1m opening, except "10-15 or 19-21" if unBAL and "11-13" if BAL
...1♦+ = "T-Walsh"
1♦ = Limited Strong Diamond: "16-18" if unBAL or "17-19" if BAL
1M = standard rule of 19-ish 1M opening except "10-15 or 19-21" if unBAL and "11-13" if BAL
1N = "14-16 BAL"

Note that Opener cannot have a standard minimum reverse after 1♣-1y/N or 1♥-1♠/N, so one could let the sequence 1♣-1♥; 2♦ correspond to the sequence 1♦-1♠; 2♦ in standard, for example.

There is also less incentive to play Gazzilli over 1M-1♠/N.

Most or all of the hands that would bid 1x-1y/N; 3x in standard are now in 1♦, so sequences like

1♣-[1M-1]; 3m

and

1M-1♠/N; 3M

could now be played as "19-21" with a one-suited hand. (No need to invent a suit just to create a force opposite a positive hand.)

And Opener cannot have a strong balanced hand after 1x-1y/N or 1M-1♠/N, either, freeing up sequences like 1♣-[1M-1]; 2N and and 1M-1♠/N; 2N.

Yes, the 1♣ opening is vulnerable to interference, and obviously more so than e.g. a Precision 1♦ opening.