`x = 23, y = 21, rule = B3/S23`

2bo6bobo9bo$obo5bo11bo$b2o5bo11b3o$8bo2bo$8b3o4b2ob2o$15bo3bo$16b3o$

17bo$4bo3bobo6bo$2bobo4b2o5b3o$3b2o4bo5bo3bo$15b2ob2o$16bobo$7bo5b3o2b

o$7b2o3bo5bobo$6bobo2bobo5b2o$12bo$15b2o$10bo3bobo$10b2o4bo$9bobo!

The 32/34-cell base is a behemoth, yes, but it's what I could do and looks synthesizable. At generation 8, the left half of 30P5H2V0 is accessible. All we have to do is attach the small right half. However, a domino from the left's creation inhibits the right (see generation 6), so that the possible predecessors are limited. I don't think it's impossible, but it's fiendish. At generation 6, the source for the right needs to look something like this:

`x = 26, y = 21, rule = LifeHistory`

.A$2.A$3A2.A.A$8.A$8.A5.3A$5.A2.A5.3A$6.3A6.A$15.A$3.A4.A5.3A$4.A2.A.

2A2.A3.A$2.3A.2A.A3.2A.2A$6.A2.A4.A.A4.C$11.3A2.A$7.A2.A7.A.2C.C$7.3A

.2A.A3.A.C2.C$7.2A3.A.A5.C.C$10.A.2A2.A3.C$10.2A3.A$9.A10.4C$18.8C$

20.4C!

Which could be derived from...I don't know, but this looks like a good angle:

`x = 13, y = 12, rule = LifeHistory`

11.A$11.A$2A3.D5.A$A10.A$2.A.2C.D2.A.A$.2A.C2.D.A.A$4.C.D.A.A$4.CA.A.

A2.A$8.A3.A$4.4D4.A$2.5DCDC$4.4D!