Yeah I'm using the unit deploy into building with free unit method. The veteran unit deploys into a veteran building (in the same way the Slave Miner retains its veterancy.)
If buildings could start veteran there'd be no problems at all but I'm pretty sure that there's no rules flags to achieve this.
I've just tested VeteranBuildings, and I tried adding the building to VeteranUnits but neither worked (unsurprisingly). Nevermind, initial veteran mine layers it'll have to be.
Actually, both the U->B->U and Infantry methods for mine laying have problems...with the one Martyr is using, minelayer gets autohealed after deploying the mine...im still sticking with the infantry method, since owner has to take care not to step on mines...
There are 3 reasons I don't use the infantry method:
1. Don't want owners to be vulnerable to own mines.
2. Can't always drive over the top of them.
3. Too tricky to bother coding.
The only problems I now have with the unit/building/unit method are:
1. Unit (and land mine) starts with 'pointless' veterancy.
2. Health (and upgrades) reset on each land mine deployed.
3. I would like hovering units not to set the mines off but this can't be done.
Joy. I've thought about that before for other purposes but there are so many other weapon interactions to consider. It's not feasable to adjust every weapon to fit and so the game's weapons become messed up.
The only thing I've found along those lines to be helpful is using ImmuneToPsionicDamage (and removing it from those that had it.)
I've already used that though.
ImmuneToVeins doesn't appear to work.
Oh well, I can live with it.
[EDIT:
On reflection, I realise that immunity flags will not stop the mine attacking/exploding. Unique armor type would be the only way to achieve hover units not setting the mine off.]