There are 5 metropolitan districts which form Merseyside from Lancashire and Cheshire and other county boroughs.

Halton Borough Council

Includes Runcorn and Widnes.
Couldn't find any car parks on the website.
These are from Parkopedia. Height information is not reliable.
Widnes - Albert Square WA8 6NF - 150 spaces.
Widnes - St Bedes WA8 6EL - 80 spaces.
Runcorn - High Street WA7 1AQ - 250 spaces.

Liverpool City Council

Not easy to find a car park. None have height information.
The only large car parks are multi storey. There are surface cp but none over 70 spaces and none has height information.
Kempston Street L3 8NG has 45 spaces.
Hunter Street L3 8EN has 63 spaces.
Lambert Street L3 8LG has 69 spaces.

Park and Ride - all p&r are operated by Merseyrail. There is parking at lots of stations but no information on height restrictions.

Mike has informed me of an
Aire at Liverpool Marina, next door to Albert Dock. Apparently this is listed in the Camperstop App with a charge of £18 per night. Thanks Mike.

Knowsley Metropolitan Borough Council

The area includes Kirby, Prescot, Huyton and Halewood.
No sleeping or camping or cooking. No MH information other than this.
The following car parks are long stay with no information about height barriers.
Huyton - Huyton Hey Road - 101 spaces.
Kirby - Hall Lane - 160 spaces.
Prescot - Cyprus Street - 53 spaces.

Sefton Borough Council

Sefton is home to Bootle and Southport and the racecourse Aintree.
There is no MH information. There is no size or height information on the car parks.
Bootle - Bootle Leisure, Washington Parade L20 5BY
Seaforth - Seaforth Vale, Norfolk Place L21 3X.
A large car park on the seafront, possibly Burbo Bank L23 8TB, overlooking the Anthony Gormley statues 'Another Place'. There are no height barriers but there are width markers and it is pay and display. This is a narrow car park and is unsuitable for long motorhomes.
There is a cycle path in front of the car park.
Lakeside Adventure Centre - The Marina ent from Cambridge Road L22 5QW 10.00 - 17.00
National Trust car park costs £6 per day, free to members. It is a huge car park and has a walk about half a mile long to see red squirrels. To get to the sea you have to cross the sand dunes.
Lifeboat Road L37 2EB - 10.00 - 16.30. April to September. 'Horsebox/trailer £10.'
Ainsdale Beach, Shore Road PR8 2QA. No size or height information.

St. Helens Borough Council

There are no MH parking bays in the council area.

Wirral Council

Buy ticket for each bay used. No overnight camping.
Some of the larger car parks.
Birkenhead - Europa Square - 150 spaces no height information.
Birkenhead - Europa Pools - 197 spaces no height information.
Birkenhead - Barton Street - 117 spaces no height information.
Birkenhead and Heswall - Pye Road - 152 spaces no height information.
West Kirby - Dee lane - 173 spaces no height information.
West Kirby - Concourse - 171 spaces no height information.
Wallasey - Seaview Road - 193 spaces no height information.