mate I have used both of the methods listed.

My Vailly 90" & 42lb Seafury uses bolts with capitive nuts. Holds them securely but if you have a heaving landing it will tend to rip the mounting and supporting structure out plus do damage to the retracts.

My smaller P51 82" and 21lbs uses self tapping screws. Again it holds them nicely but on a few occassions I have had heavy arrivals and it has pulled the screws out, sometimes with a little sheet damage but not substatial and the retracts have not been damaged.
The rails tend to split and will need to be repaired or replaced. Not really a big repair.

Pros and cons to both methods.

On a smaller model like yours I think the self tapping screws would be a good option.

Hope it helps.
cheers
P