Looking back over the years, I started modelling in N gauge in 1974 on leaving the RAF after 23 years service, father had just died so mum needed support. Father had started modelling N gauge a few months before so I inherited 2 locos some other stock & track. Locos were a Fleischmann 711 4-6-0 and an Farish 0-6-0 tank.
For a few of years I tried various things basing a layout loosely on the East Dorset area and BR stock.
After about 5 years of this family disintegrated wife was spending more than I was earning, so divorce and went to live with mother, tried setting up a loft layout. In '83 I remarried and after a year or so in digs without much room for a layout we bought a house, that's when modelling took off
Layout was in a bay window and Southern 1930s settled on for period and staying wiyh E Dorset.
by this time the Fleischman 7161 had acquired a Langley S15 kit and as we all know the manufacturers almost ignored the SR so it was all much of the stock was kit hack or bash.
One advantage of modelling was the possibilty of including LMS stock via the Somerset and Dorset line.

The following may be of help to others who like the Southern yet have problems getting suitable locos.

4-6-0s, we have 2 kits, Langley S15 and BHE N15; it is possible with a bit of swapping parts and a few hacks to produce most if not all the variants of the two classes and also the H15. For all 3 classes it is possible to produce the variations; one glaring problem with the BHE kit, designed to take a Black 5 chassis which is so wrong for an Arthur, wheels too small and wrongly spaced you need 7'6" drivers and spacing of the rear drivers are more widely spaced than the front
Most noticeable difference is the cab roof both kits have the earlier Urie LSWR cab roof,for that either attack the one in the kit or make a new one , card or metal will do the job, work from photos or scale drawings; (Bradley's LSWR locomotive books have drawings)

Tenders, luckily the kits have different tenders, Langley have the Drummond watercart, BHE have the Urie one; the Drummond Watercart also comes in handy with Fleischman tender drive to put behind a T9 from Union Mills - at the same time hack the cab sides and splashers on the loco for the narrow cab version. You now have a spare UM tender drive, it will fit into the BHE tender plus an extra pair of wheels.

Other hacks for other variants, some S15s had a step up in the footpte over the cylinders,     smoke deflectors earlier period they were not fitted. You can also hack an H15, y using a chassis with 6' drivers (IIRC one of the Farish LNER 4-6-0s will fit)
For a Nelson I hacked a Jubilee
Some of my SR 4-6-0s ended up on Ebay, I'd be interested to hear if the are still running.
 H15 491, S15s 509,837 Nelson 862, N15 742, other escapees, K10 4-4-0 387 (scratch built from Brass' Q class 0-6-0 536 hacked from a 4F.
Dapol M7s if used for Push pull working, need the pump on the side of the smoke box, but also need the front footplate extended, cut it off stick  small piece of plastic underneath then stick the cut off piece back on about 1/8" forward and fill the gap. For Push pull coaches I cut the end off each side, leaving the floor and end intact cut windows in the end-easy enough to guesstimate size from photos  same with pipe work, swap the side pieces over such that the doors are at the end.
Don't know if this link will work,
https://photos.app.goo.gl/BYAur4aifnUbues36
I still have a few items left and some Kato track but they only get the occasional outing, at age 92 mobility and associated problems tend to preclude much action.

@Dorsetmike

...and let's not forget the "ON_NACC". (Oh No, Not Another Controller Circuit!). 

I recently built another ON_NACC and filled the pulse with 25kHz from a PWM controller and ran the pulse through an op amp so I could control the amplitude, before mixing with the DC.
The lttle PWM board is also very nice on its own and I run it from a variable supply to set the PWM amplitude to suit the loco type.

Mark

So you've now been modelling the southern railway for twice as long as it existed