Your hope has been answered...new build just put up includes code to allow IS Partial Wings
Bless you.
As for how effective Partial Wings are compared to same-MP with iJJs:
Partial Wings are generally also more space-efficient.
20-Tons 6/9/8: 4.5t vs. 8t
25-Tons 6/9/8: 5t vs. 8t
30-Tons 6/9/8: 5.5t vs. 8t
35-Tons 6/9/8: 5.5t vs. 8t
40-Tons 6/9/8: 6t vs. 8t
45-Tons 6/9/8: 6.5t vs. 8t
50-Tons 5/8/7: 6t vs. 7t
55-Tons 5/8/7: 6.5t vs. 7t
60-Tons 5/8/6: 9.5t vs. 12t
65-Tons 5/8/6: 10t vs. 12t
70-Tons 4/6/5: 9t vs. 10t
75-Tons 4/6/5: 9.5t vs. 10t
80-Tons 4/6/5: 10t vs. 10t
85-Tons 4/6/5: 10t vs. 10t
90-Tons 4/6/5: 14.5t vs. 20t
95-Tons 3/5/4: 13t vs. 16t
100-Tons 3/5/4: 13t vs. 16t
And that's just IS Partial Wings.
The 100-Tonner moving 3/5/4 would be 11t vs. 16t for the clanners.
a 5/8/9 'mech for relatively reasonable tonnage
Yes, if you consider about 33% of your 'Mechs weight as reasonable. (60-Tonner)
Although on a 55-Tonner its only 10t (in which case: why not go for 4/8/10?).