That sets alarm bells ringing straight away.
Any odd-sized slots on a mining ship should be reserved for Collectors whenever possible.
Personally, I always use bi-weaves on my mining ships.
The constant bashing against roids is a far bigger hazard than the threat of attack.
As for the recent question that
@Limpooka asked, the simple answer is always to check with Coriolis or EDSY.
Use those websites to build a ship then look at the resistances as well as the overall strength - and THEN look at the "defence" tab (in Coriolis) to get info about stuff like how long a shield will last or how long it'll take to regenerate etc.
FWIW, Coriolis also allows you to evaluate your ship against another hypothetical ship in hypothetical combat... hypothetcally.
It's worth designing a murder-hobo FdL in Coriolis, saving it and then using it as the comparison to see how your own ships would do against a murder-hobo ship.
You might, for example, feel pretty smug because you've designed a ship with a gazillion mj of shield but then you'll find that a murder-hobo FdL will chew through that in 10 seconds with a bunch of overcharged MCs and PAs.