Is there a "portable" version of a whacker, or alternatives?

A whacker should fit through the house, 2 people can carry it. Or even roll

It in.

How did you get the hardcore there?

I rented one which was about the size of a folded lawnmower, should fit through a house although would be easier with helping hands as they're heavy enough

Just be careful to keep it level or petrol might spill

My understanding is that with the lighter ones you'll need to do more passes than the guidelines would recommend

I also found it helpful to use a long length of timber to initially tamp it down and also to spot any uneven areas. It seemed to help the final compacted surface to be level

Yes, a tamper.

The thing with compaction is that it's critical for two aspects:

• Where you have a lot of load bearing
• Where you have layers that are unable to accommodate settling without cracking.

For instance, a concrete slab (or pavers) for parking cars on is going to need a rock-solid base because there are large point loads which will cause the slab/pavers to crack if the base moves.

You're not building a house, you're laying a patio, and as long as there's no topsoil beneath the aggregate and what's above the aggregate is able to accommodate a bit of movement, I'd say you'll be grand.

you probably want to what 3 5cm layers ratther than try to do all 15cm in 1 go, especially with a small or manual one

there are "big foot" ones that will easily go through a door